Dragic would be an upgrade over Collison, and he'd help form a very good trio (Dragic, Gay, Cousins). That could be the catalyst to take this team back to the play offs, especially taking into account Ben McLemoe improving, and the possibility of drafting a player that could step in at PF (eg WCS), that would create a solid line up.
The main problem with this is that Dragic will likely command a bigger deal than we can afford to pay unless we dump some salary, and even if we clear space, our rotation will take a hit because we won't have much to offer to form a strong bench. So while the trio would be fun to watch, I think we should possibly look at trying to acquire this type of difference maker at PF and ride with a solid, if unspectacular, PG in Collison.
And to be honest, I think staying with Miami is the most likely scenario. He'll get a big pay day there, and in the eastern conference he'll have an easier ride as long as Wade and Bosh stay healthy. Plus they've got Whiteside at center and Deng at SF to round off a decent line up.