With Rivers going to the Clippers, the league not allowing Garnett (who supposedly wants to play one more season) to join him, Pierce highly likely to be traded by the end of the month and the Celtics clearly beginning a re-build, or at the very least, a re-load, if I'm the Spurs, I call up the Celtics and offer Diaw (after he inevitably opts in . . . Bonner wouldn't work, because they have to make a decision on him the day before their cap space comes into effect) and a future 1st for Garnett.
I realize it's probably a long shot to convince him to waive his no trade, but it's worth a shot. They can have Pop and Duncan (I think he'd be on board) sell him on taking 1-2 final shots at a championship, potentially having another crack at the hated Heat and being able to go back to playing his natural position.