Honestly, I'm failing to see how they upgrade their roster without significantly changing the roster. I just don't think the threesome of James, Irving, and Love will work as a title contender. Two of your Big Three cannot be God-awful defenders for you to be a title contender. Say what you want about Wade and Bosh, but they were at least two-way players.
I actually think the first move is to try and trade Irving, because he's just not the greatest fit at point guard with Lebron. In fact, Lebron has never really excelled with a really high level, ball-dominant point guard like Irving (recently at least), because Lebron has always been the de facto point forward for his teams.
What makes the most sense is an Irving for Paul trade, though I highly doubt GM Doc goes for that. Would Irving and a future unprotected first round pick for Paul work? Doubtful.
What about going unconventional and trading Irving for Butler? Chicago is wanting a franchise point guard to build around, and Butler shares a lot of similarities with Wade. That's probably a straight-up trade for both teams that makes sense.
What about Love? The popular trade is for Melo, but I think they'd ultimately be worse with Melo than Love. There's also potentially trading Love for someone like Cousins, but I really don't see that working either.
How about a Love and a future first for Griffin trade? Love is locked up long-term, and he actually spreads the floor more for LAC than Griffin. DJ is also the perfect frontcourt pairing with Love due to his athleticism and ability to help cover for Love's deficiencies. For Cleveland, Griffin isn't a perfect fit at 4, but he provides more athleticism and better defense than Love. So how much better would this Cleveland lineup be than their current lineup:
PG: Smith, Delavedova
SG: Butler, Shumpert
SF: James, Jefferson
PF: Griffin, Frye
C: Thompson, Mozgov
That lineup looks pretty weird to me, and I question how well it would work with that much less shooting in the lineup.
It won't be the way they go, but I think they need to get out of the "Big 3" mindset and look for more high-end role players that fit well with their core. If I was Cleveland, I would move James to the 4 and try to trade Love to Boston for Bradley and Crowder, who make much more sense as non-ball-dominant, floor-spreading, two-way defenders than what they currently have. So there lineup would be:
PG: Irving, Dellavedova, Williams
SG: Bradley, Smith
SF: Crowder, Shumpert, Jefferson
PF: Lebron, Frye
C: Thompson, Mozgov
That's the type of lineup that you're going to need to get past the Warriors. You have two guys in Bradley and Crowder who can spend their entire focus and energy on limiting Curry and Thompson, yet they can also hit open shots for you on offense.
Granted, I think Danny would almost say no to that deal right now. Though these guys aren't stars, we forget how valuable these high-end, cost-controlled role players really are for us.