A lot of people are on point here... If Rondo is being traded, the reason is clearly to make a push at the championship this year. If that's the case, we do NOT need a 2, 3, or 4, so we would need to trade him to fill a newly found hole at PG or a C. This player would need to be a playoff impact player. Here are the ONLY possible candidates that I see at those 2 positions:
CP3 (possible)
Deron Williams (highly unlikely)
Rose (impossible)
Nash
Westbrook
Dwight Howard (unlikely b/c of current team rosters and salaries)
Marc Gasol
Andrew Bynum (not happening)
If CP3, Nash, Westbrook, or Gasol aren't coming through that door, I don't want to trade Rondo. And even the latter of those 3 would need to bring extra players along with them.
On the topic of scoring, I think CP3 would be perfect. A scorer who's penetration will also get Ray a lot of open looks. As others have mentioned, it is a no-deal without a contract extension though.