I think those people who are saying you'll see a different Rondo next season are right. I expect to see more fluid offense, and more effort on defense. However, I also don't think he's as good as some people rate him. He's not a top 5 point guard even when healthy. He is, however, a unique point guard that can excel in the right circumstances (on a team with a bunch of shot makers). He's one of the better playmakers in the league.
Because I don't think the C's offense is currently set up for him to thrive in, and because he can walk in 2015 (the C's could overpay for him - I hope they don't though. He's not a max player IMO. I think 5 years/$12-$14M is the most I'd want them to go for him) I think trade is the best option. Ideally, I'd like to see them actually get a bona fide NBA starter back to play PG or C (not just picks) so that the team isn't too inexperienced, but I'm not sure what he's worth right now.
The Lakers deal for Nash (Nash isn't exactly what I had in mind for NBA starter PG) plus pick that has been tossed around this board a few times might be a realistic one that could be on the table come draft time. I'd think about it if I'm Ainge. I think more likely though, he'll be the starting PG come game 1 of '14-15 because I think Danny is fond of his game.