The only team in the league that would even think about bringing Duncan off the bench is the Lakers. He'd be guaranteed to start for every other team in the league.
I've heard the "Duncan off the bench" thing a few times now and it's flat out ridiculous. He finished second among centers in PER (14th overall; 1st on Spurs). I'm not saying PER is the be all end all, but go and look at the list. The top twenty are pretty much a who's who of the best players in the league.
He's still one of the best all around bigs in the league and is good for 28-32 solid minutes most games. He just needs more help; it's that simple. He can't be paired with undersized, limited players and specialists. He needs a legit starter next to him. Splitter can be that guy, but they need someone else, as well. Someone who, when it comes to finishing games, has the capacity to not be a liability on either end.
A guy they should take a look at is Blatche. I explain why here:
http://www.spurstalk.com/forums/show...124967&page=24
No matter what they do, it more than likely is too late. But that doesn't mean they shouldn't try. After all Duncan's done for this organization, at the very least they owe it to him to continue to try to contend for his (presumed) final season or two. I'm not talking about making some insane trade that robs them of Hill and/or Splitter for some aging big. But there are realistic trades out that that can improve this team short term, while serving as a bridge to the future.
They can re-build when Duncan's gone. They'll have plenty of time to. For now, keep trying. They owe it to him and besides, it's San Antonio. It's highly unlikely (and that's being generous) they'll get anything close to another Duncan/big three.