I've been pretty impressed with what Stan Van Gundy has been able to do in Detroit, and if i'm in charge, i think i attempt to make a team in the same mold, and surround Boogie with shooters next year. Either Gay or Rondo can and should stay, but not both. Rondo has been averaging an insane amount of assists this season, in an ill fitting system with ill fitting parts. If he's got Boogie and numerous shooters (think R. Anderson, Nic Batum, Harrison Barnes, Kent Bazemore, etc) i think he can be an excellent fit to the puzzle next year, especially since he's bonded and has the respect of Boogie.
On the other hand, keep Rudy, let Rondo walk, you have a legit #2 scorer who (in theory) could take over a game in Boogies absence - this clearly wasn't the case this year, but in theory, with the right coach/system, Rudy is a nice player to have. I just don't think he fits well with Rondo and Cuz, since all of them are weak outside scorers, and need the ball to be effective.
I know defense is a big issue right now, but i honestly feel like team D is more important than getting a "premier wing defender." Team D is all about being in the right system, and i think if we had a different coach this year, we wouldn't be stressing about our lack of D nearly as much as we all are right now. Not saying ONLY pick up offensive players in the offseason, but find players that fit the mold of being solid shooters 1st and foremost, *get the right coach/system that emphasizes D, and i think we'd be in a good place next year.
In summation - keep either one of Rudy or Rondo, fill all other slots with shooters to open up the lane for Boogie and balance the scoring, then get a coach and system that actually emphasizes D. And if that doesn't work, blow it the f*** up, and let's move on