To me, the only reason to rebuild is when your nucleus of talent is old and have little chance to compete for a le. Which, pretty much describes the Spurs. If the Spurs played in LA, Miami or NY, then it would be easier to just RELOAD w/ top notch talent but there are few top 5 in the league talent that really want to play in SA.
SA's formula for success in 1999 and since has been to DRAFT well. TD, Parker, Ginobili were all drafted and became elite. The role players were all trades or FAs. This past draft was a weak one. The Spurs should just bite the bullet, play the younger players (Anderson, Splitter, Leonard) and see where the chips lie. If they're lucky (YES, LUCKY), they'll become a lottery team NEXT year when the draft is strong. Maybe they'll be even luckier and get a top 5 pick and draft the next PF of their future.
That my friend, is REBUILDING. I know lots of fans don't want to hear it, but at the current rate of success (make playoffs and lose), they will never get a draft pick good enough to get anyone of value (they had to trade Hill to get a pick just outside the lottery in one of the weakest drafts in history).