According to Patricia Bender's site, Tim has a player option in '08.
Even if he has a PO in '08 or '09, I doubt he'd give up $20M a year to play for another team that might have a shot at the championship.

In 2010, he re-evaluates how he feels physically and how well he thinks the Spurs can do with the current roster make-up. If he's old & tired, and the Spurs have botched any real chance he'll probably retire....

But I doubt the Spurs are going to be bad enough for him to give the game up....I'll stick with my original prediction.

2yr, $15M deal in 2010