The problem with the Sansa/Arya twist is the scene where Sansa snuck into Arya's room. If they were conspiring together, there was no reason to have a confrontation behind closed doors with nobody else in the room.
Thought it was funny when Cersei called Jamie the stupidest Lannister. Although I think Tyrion is giving him a good run for the title. How many more times can his advice be wrong before Dany changes his position to court jester?
Cersei's plan won't work. Jamie was right, whoever wins in the North will march South and wipe her out. Her only shot was one of unity, especially if she stayed behind and Jon and Dany both died in the fight with the dead. She could have then taken the position, that I'm sorry they died defending us, but we lost a lot of good men as well. I did right by the kingdom, bend the knee. Her tactic will only serve to get her wiped out.
Of course it won't because this is a show and they're not going to let Cersei win in the end. The fans of the show would hate that. The Night King will be defeated. Theon and the Hound will get their redemption even if they end up dying doing it. Cersei will be defeated. Only question is how. My guess is Jamie dies valiantly in battle. Arya takes his face and kills Cersei. The only real question is what happens between Jon and Dany. I suspect that will be addressed by her becoming pregnant.
Unity and hoping Jon and Dany die in the fighting is not a plan for victory. If Jon and Dany die, the dead most likely would have won. Letting your two enemies fight each other while you build up your forces is a good plan.
Cersei correctly surmised that one of the dragons is dead. If one dragon can die so can the others. Without the dragons, Jon and Dany's forces are very beatable. There were only 8000 Unsullied to start and at least 1000 should already be dead from fighting. Robb Stark's northern army only had 20K men and they were pretty much wiped out. The Dothraki are impressive but they aren't made for conducting sieges. If Jon and Dany defeat the dead, their forces will be significantly depleted.
Meanwhile Cersei is rebuilding her forces. 20k Gold Company mercenaries are on the way. Euron controls the seas. More ballista can be made. More wildfire can be produced. The way Qyburn was looking at the dead remains, I wouldn't be surprised if Cersei has her own dead (or half-dead) army.
They can't defeat the Night King without the dragons. Thus at least 1 dragon will survive the fighting. Cersei also just isn't likeable. The people won't be on her side, which will eventually lead to her downfall. You can't keep power for long if no one wants you to. She is taking a position that will lead to the other side being the one the people back (unless it is the army of the dead). If they see any crack in the shield, they will bolt to Jon/Dany, especially as the whispers of Cersei's betrayal become louder and louder.
Obviously at least one dragon will survive since it is a TV show but that is not a given. Valyrian steel and dragon glass kill white walkers. The dragons are needed for mass destruction of the dead. Of course, wildfire would work quite well against them too. As for the dragon, just need a bunch of the ballista.
What world do you live in? Brutal tyrants keep power quite well. Now and throughout human history. The people generally don't matter. It is the important power brokers that do. Hence her move to get the Iron Bank on her side. Cersei may not be liked but she's been an efficient and steady ruler. She's not oppressing the people. They are free to go about their daily lives. She's also a southerner.
Why would southerners flock to Jon and Dany? If I'm a southerner, I'm quite happy not to be sent north to fight and die. Jon is a northerner and Dany is a foreigner and they are both Targaryens. There is no desire to be ruled by Targaryens again after the Mad King. Refer to how the threat of Dany, the Unsullied and Dothraki was used to turn the Tarlys against the Tyrells who they were pledged to.
Even with the Golden Company, Cersei doesn't have the army to control the south, let alone the north once that army marches back down south. Remember the Golden Company is 20,000 troops, but a million people live in Kings Landing alone. She can't keep the peace without the support of the other great houses (or whatever is left of them) and she absolutely needs the resources of High Garden, Dorne, etc. to survive and pay back the Iron Bank, but she doesn't have the forces to keep those lands without the support of those people and their lords, and she won't get it because she is a tyrant. Tyrants keep power when they have the military force to keep power, Cersei quite simply doesn't have that and she never will. It is only a matter of time for her. Her treachery might buy her a bit more time, but the end game is the same, and not just because this a fantasy, because Martin could easily end this series with a tyrant on the throne, it is just that Cersei isn't the right tyrant. Frankly, I wouldn't be overly surprised if there is a tyrant on the thrown at the end. I just think it would be far more like to be Dany, as I can totally see her going full on villain. She has that cold viciousness that Cersei does and she could easily be triggered into a downward spiral (you know if her dragons die, Jon, Jorah, Tyrion, etc. all die as well). She will still defeat Cersei though because she will be much better positioned to do so with the better trained forces and the full support of the north if she leads the defeat of the Night King (she also would more than likely have the 3 Eyed Raven on her side). That said, I believe Dany dies and Jon ends up on the thrown after he defeats Cersei. As this has always been his story and that of his "siblings". Everyone else is just filler to get the story to the end point.
A couple thousand gold cloaks have kept order in King's landing. Do you see any rioting in King's landing? All that food in High Garden got to King's landing. Popular uprising don't occur that often and when they do they are usually quelled rather easily by brutal Tyrants. Dorne and High Garden forces have already been defeated. The Lannisters have by the best and largest military forces in the South. There is practically no one left in the South to challenge her. Only the Knights of the Vale really remain. As far as leaders take away Jon and Dany and there's no one left to lead a revolt. Cersei already paid off a huge debt to the Iron Bank. If she wins, she'd have no problem paying off the debt for the Gold Company.
You ignore that the North is much less populated than the South and that much of their fighting men have already been killed. When Jon fought Ramsey Bolton, he had 2000 men including wildings and Ramsey had 5000. Those were all Northern men on both sides that got slaughtered and only the Knights of the Vale saved Jon from his own stupidity. Assuming Jon and Dany defeat the dead, many of their remaining forces are going to be killed doing so. Take away the dragons and Cersei would have a far superior hand. Heck if Dany and Jon are stupid enough to keep traveling by ship Euron would wipe them out.
Another significant advantage Cersei has is Qyburn and his little birds. They'd learn of any plots against Cersei before they were able to become a real threat.
the gold cloaks kept the peace when the south was all behind one ruler and no other legitimate threats to the throne existed i..e. when the tyrant had all the power. The golden company is an army of mercenaries those aren't reliable for anything. They will leave as soon as it looks like they will die. You can only buy support for so long.
The Golden Company are mercenaries who will fight and die as long as they are getting paid and they've got a chance to win. What other leader are southerners going to follow? Jon or Dany? A northerner and a foreigner and both Targaryens. Although most southerners would dismiss Jon's claims of being a Targaryen and rightful ruler. Dorne and High Garden joined up with them and got wiped out. You don't see southerners flocking to Jon or Dany. If they defeat the dead in the North, the southerners won't even know about it except for some rumors that they'll brush of as northern nonsense.
Why would southerners want Dany to win? She'll remind them of the Mad King. She brings dragons which is bad. She brings Unsullied which is bad. She brings Dothraki which is really, really bad. Cersei and Jamie already showed how easy it was to use that against Dany by getting the Tarlys to turn on High Garden. Of course, the stories of how Dany burned the Tarlys alive will be thrown into the mix too. Most southerners won't Cersei may not be loved by southerners but neither is Jon or Dany. Except for fear most southerners have no reason to support Jon or Dany.
The Tarly's turned on High Garden because they were going to lose. But that is the point I'm making, the only ones with true loyalty are Jon and Dany. Cersei doesn't have loyalty, which means they don't really have support, only fear. Fear is powerful for a ruler when there aren't other options, but there will be other options here.
And let's think about the Southern "heirs" still alive. Edmure Tully, Robyn Arryn, and of course Samwell Tarly (though not a "Great House"). The Tyrell's and Martell's are seemingly wiped out and the only Baratheon left is the
Edited for profanity. Please do not do it again. Gendry. Plus, you have Brienne of Tarth a mid-tier house. I'm sure there are plenty of other lords not on the show or in the books, but they won't provide much as they aren't great houses. All of the named people will support Jon and/or Dany. The Highgarden and Dornish forces are basically destroyed. The Lannister army isn't what it once was. An "army" of mercenaries won't win a war like this and Euron and his ships only work on the water, this won't be a water fight. Besides one dragon pass and the ships are all gone in an instant.
Cersei has virtually no shot at winning. And you keep mentioning the "Mad King" and act like Cersei isn't a "Mad Queen". She is just as crazy as the Mad King, and her actions will absolutely be known. And you know those are recent events not 20 years ago.