Although if Boris really is making that kind of power play, why doesn't D-Cam just deselect him from Kensington or wherever he's standing? He isn't an MP. I really don't think there are that many Boris loyalists. He is a nasty bastard hiding behind that ruffled buffoon exterior, plus surely their next leader has to be as far away from Old Etonian as possible.
Boris is quite popular amongst the grass roots. Plus with the 'anti-politics' sentiment washing around at the moment it would be a far too overtly political mood. Cameron would be the guy who stabbed a rival in the back for his own ends.