Just for what it's worth, here are salaries for next year if Spurs do a Thomas/Salmons for expirings trade:
...
Total: ~$67,000,000 for 9 players
Then, do the Spurs feel they can afford to resign Manu for $6-8 million and Splitter for $3-5 million, plus 2-4 other minimum-type players? Hard to say. Best guess estimates would put that payroll at about $82 million, which is more than this year, plus with more luxury tax.
As a few have mentioned, this would likely yield trading RJ and/or McDyess and/or others, but there's only so much you can trim off the payroll that way.