maybe Mark Roman gets traded? Maybe he gets cut? Maybe the 49ers draft a safety at somepoint? And maybe Dashon Goldson wins the job and becomes an All Pro? That would be the best case.
But I've always been intrigued by the possibility of turning a guy who was once an Ace corner into a free safety (see Rod Woodson, even Merton Hanks). I bring this up because some dude on Yahoo sports has an article about FA's and Chris McCallister is on the list. He's lost a step to be a top corner maybe. But he still has instincts and might be a nice saftey for someone if he was willing.