There is no player in the NBA less likely to wear a Celtics uniform during the remainder of his career than Rondo, short of him signing one of those one day contracts before he retires. I'd bet on Tim Duncan playing for the Cs before I'd place the same wager on Rondo.
For anyone who doubts me, know this: Rondo is NOT well liked in the Celtics organization, and that's putting it mildly.