It's easy to say that if the 49ers cut him he must be washed up but I actually wouldn't be stunned to see the Pats give a try out to Thomas. Belichick obviously really respects Sean Payton's shemes and players, and while Thomas is obviously not an explosive player now (if he ever was) he would probably come cheap and has decent hands, if memory serves.
Edit: still, White and Bolden are the most likely candidates to fill the role, and I'm not sure they'll bring anyone else in.