Would be a big shock if he chose the Celtics. Has the chance to play with an up and coming team in the Cavs or with Lebron James in South Beach. Those are the two places he went to school/grew up as well IIRC.
In the end he's going to go to the Heat. He's a better fit in Boston or Cleveland, but South Beach, Lebron, and the destination 95% of all players want to play at for the chance of a dynasty.