I don't think Ozzie's capable of playing SS anymore. Not so much because of his arm strength (or even his range), but because that goofy hitch in his motion has become more and more pronounced the longer he's been at 2B. It's not just the hard throws I think he'd struggle with - I'm afraid he'd turn some of the routine plays into really close ones and infield singles for strong runners.
As for letting Dansby just play his contract out, that's probably the best approach to the situation - I'd just hope AA would leave himself enough flexibility to offer him a shorter/below-market extension in the event he continues to improve and/or Shewmake struggles again coming out of the blocks next season. Ideally you can avoid spending the type of money next year's SS class is going to make and still get strong production at the position, but if Dansby keeps producing I wouldn't think twice about trying Shewmake out in the outfield early next season to see if you can get Dansby at SS for half the money the other guys get so you can spend that money on pitching.