I'd say Bosh, with his Texas ties, admiration for Dave and Tim growing up, would be their best chance at the top-tier of free-agents, but still not a very likely scenario.
A guy like J.Johnson or someone who falls just below the very top-tier of free-agents is probably what you can expect if the Spurs are able to land a big-time free-agent in 2010.
The Spurs actually might be better off though getting their guy from one of these teams looking to free cap room for 2010.
There should be some opportunities for some Gasol like deals with the desperation of some of these teams looking to free cap room, so if I'm the Spurs that's what I'm looking to do.
Afterall, if you can get a quality player that helps now, why would you let the core of this team get two years older and mortgage your future on a slim shot of landing that mythical big-time free-agent?