I should further note, that is simply a list of players. It does nothing to address the Spurs side of the equation (ie. who would fit), nor does it address incentives needed. I think to move Jefferson's contract, incentives will be needed for almost all of these players.
From my perspective, assuming Splitter is coming and does pan out, I would not expect the FO to get a big. We can currently expect to have 4 decent bigs next year (and 3 the following 2 years) - Duncan, McDyess, Blair, Splitter.
Similarly with Parker and Hill, PG is a pretty full spot. However, it should be noted that moving Parker with Jefferson might be an option as an incentive; at that point, getting back a good PG would be important. Assuming not moving Parker, a PG received would have to be able to run 2 PG sets with Parker (ie. be able to cover SG's defensively; Parker isn't big enough to do this).
This leaves the wing spots, which is clearly the point of greatest weakness on the team. All of our current wings have significant flaws: Manu has injury issues, Hill is undersized, Jefferson has no balls/brains (he apparently has the physical ability and skills, just doesn't do it 90% of the time), Bogans, Mason, Finley (well, the less said the better about these 3), Hairston is mildly undersized and significantly inexperienced (and that lack of experience may be hiding other flaws, which will only come out with playing time).
This analysis short lists the following candidates:
Iguoalda
Deng
Maggette
Ellis
Gerald Wallace
Stephen Jackson
Richard Hamilton
Kevin Martin
Danny Granger
Turkoglu
Arenas
My own personal preferences would start with
Iguoalda
Deng
Danny Granger
Ellis
Pretty much in that order.
This is primarily driven by youth, and my estimation of fit in the Spurs scheme. I think Iguolda and Deng would be much the preferable options (Granger would be nice, but I doubt he is actually available... Bird is hanging on too hard to a team thats flawed at it's core.) Ellis is last because a) he a bit undersized b) seems a bit of a headcase and c) I'm not at all sure he'd fit well with Parker.