I don't know that I'll ever understand the Rudy Gay love around here. He's a good player, and, in a vacuum, he's better than someone like Iman Shumpert. That's obvious. But what kind of role is he playing here? He'd basically be asked to play some hybrid RJ/Shump role. I think some view him as this team's Andre Iguodala, but AI works for GS because he keeps the ball moving, can defend four positions, and can play PG allowing them to move Steph off the ball.
Rudy can't play the PG, he's an average defender at best, and he's a notorious ball stopper. Not only that, but he's not a very good three point shooter, and you'd be asking him to take a serious step back in role. He's not starting, and he's maybe playing 20-25 mpg. What's the point in this team moving it's limited assets for that?
A couple thoughts:
1.) You might not have to trade a ton for Gay, because Sacramento is going nowhere this year and Gay isn't going to resign there. Also, other teams might not want him because he will be gone, or have a huge contract after the season. OTOH, playing for a championship might convince him to opt into his player option next year (can discuss that with him during the deal, I believe?). I honestly think Shumpert + Felder + Osman might get it done.
2.) Gay is too good not to start, and that of course produces some problems integrating him into a lineup this quickly. The first thought would be to start him at the 2 (KI/Gay/LBJ/Love/Thompson) --- but especially against GS I might start a lineup that is (KI/Smith/Gay/LBJ/Love).
I think the smaller lineup destroys GS. Every player in that lineup is a 3PT shooter, which produces ridiculous spacing. There's also three drivers in KI/Gay/LBJ, and you should be able to PnR Curry onto one of them consistently (they will have to switch PnRs because of the three-point shooting).
Defensively, You can hide Love on Zaza, and switch Smith onto Curry and KI onto Thompson to start the game. LBJ/Gay switch off on Durant/Green. This allows you to switch every Curry + Durant/Green PnR, and also to avoid forcing LBJ to cover Durant too much. GS will probably try to pick with Thompson to force KI onto Curry, but I think KI on Curry is not as bad as the offensive advantage you get from that matchup.
Finally, this lineup is big and athletic. It still rebounds well on both sides of the ball with Gay/LBJ/Love.
3.) You now can rest LBJ about 10 MPG in the finals, and have lineups on the court that look like: KI/Smith/Gay/Love/Thompson. Those are still really good lineups, and functionally they can run all the sets that the Cavs are used to running with LBJ in the game. This should make the adjustments to integrate Gay much easier than it would be when you add a typical star --- he's really poor man's LBJ, and is used to getting the ball in similar circumstances.
Similarly, when KI rests in the finals you'll have LBJ at point foreward, and now Gay becomes a much better Richard Jefferson.
4.) Without another guy who can guard big 3s and 4s (which we currently don't have), you're going to run into a problem in the finals with LBJ -- who can only guard either Durant or Green. Last year we were successful when we put LBJ on Green and switched to shut down the Curry/Green PnR. Durant sort of prevents us from doing that this year, because if LBJ is on Green they put will go Iso Durant against Smith or TT. Gay solves that problem.
Ok, I'm done with the wishful thinking. This will almost certainly never happen.