I don't agree about the "untouchables" label. A lot depends upon what happens this season, in terms of the Celtics and everyone else as well. Here's how I see it:
Untouchable:
KG - He sparked the turnaround, is still a great player, a unique talent, and irreplaceable at this point. The ill-will from trading him now would be terrible.
Pierce - Face of the franchise, deserves to retire as a Celtic. I don't care if the C's don't win another title during Pierce's career, I want Pierce to be one of the few players of this generation, along with Duncan and Kobe, to play every game for one team.
Everyone else is tradeable, as in if the right deal came along, they could be replaced. In reverse trade order of the starters (most important to keep listed first) I go:
Rondo - Young, great defense, one the rise still.
Perk - Size, young, toughness, defense, rebounding, cheap
Allen - Getting up there in years (33), least important member of the Li'l 3, least emotional/fan attachment of the starters, sharpest decline last year, most replaceable skills.
I don't buy that Ray Allen is the only shooting guard who could fit with our current starters. Our team would be different without him there, but there are other players who could help the C's win titles. His defense is certainly replaceable. He's a fantastic shooter, so there'd necessarily be a dropoff there, but that could be replaced by improved D and penetration, which Ray noticeably dropped off in last year.
Anyway, the above logic is why Ray is the focus of a lot of potential trade ideas. Most replaceable of the big three, a very un-talked about decline in production, with a large and short contract. I think there are some trades involving ray that would have positive consequences down the road, especially if you are thinking about trying to remain competitive now and bridge to a younger generation. Trying to think somewhat realistically and outside the box:
Utah
Boozer might bolt to a bigger market, so this is contingent upon his signing an extension with boston upon the trade(he's only 26). Boozer may walk anyway, so Utah wants to get something. Utah still needs outside shooting and has always lacked a truly great shooting guard. If they get Ray, they can slide AK back up to his best position at PF, surround Derron Williams with some great shooters to open it up and let him penetrate and dish. For us, Boozer is a young stud, can really help on the glass, and alongside KG he can hide some of his defensive shortcomings in terms of shot blocking while bodying up on stronger, bigger post players. If you are worried about losing Ray's shooting for spacing, remember that Boozer would be replacing a lot of Perk's first team minutes, and with Boozer and KG, the middle remains open as each has consistent range from 15-18.
Trade:
Ray, BBD, lottery protected 1st for Boozer, Brewer, Harpring (salary purposes).
Clippers
If the current team doesn't work out, look for friscal (fiscally frugal) GM Baylor to try to dump some long term contracts. The Clippers still need a stud at the 2/3 and Ray is an upgrade there, while Camby/Kaman is a bit redundant.
Trade:
Ray, BBD for Kaman, Mobley
Knicks
I know this one will have no takers, but remember, out of the box thinking. One of Randolph's problems in New York is redundancy with Curry, as in the get in each others' way in the post. Not a problem with KG as the other big man, as he can draw his guy out. KG can also get his back on D, and I bet that Randolph's effort rises from "catatonic" to at least "mid-level torador" on a good competitive team that stresses good D. And remember that Randolph is considered a negative, so you can get some good chips too, probably, for the future.
Trade:
Ray, BBD, for Randolph, David Lee, and an unprotected first
New Jersey
Again, probably a lot of resistance to this idea based on reputation. Remember that just because Carter seems to not reach his potential doesn't mean he isn't productive. Quite the opposite, he's still productive, even more so when he's interested, like he would be on a good team like the C's. Likewise, on the C's he wouldn't be expected to handle the ball as much, and he's actually a very good catch-and shoot shooter and a much better penetrator than Ray. he's also better on D even when he's not as motivated. And, like with Randolph, because NJ is looking to clean house, there's a good chance of getting extra goodies.
Trade:
Ray for Carter, Sean Williams, the better 1st rounder in 2010: Dallas or NJ.
Phoenix
Don't really see this happening unless Phoenix is really bad and needs to clean house. Even if this is the case, I see them building around amare rather than trading him. But if Amare makes it clear he wants out of phoenix if the season goes downhill, it might force their hand. If so, he'd need to sign an extension as part of the deal and we'd need to take back some extra crap salary as well. The deal below saves Phoenix a lot of money and helps get them some picks back.
Trade
Ray, Scal, 1st rounder for Amare, Diaw
Ok, tear it apart.