of course it will depend on the marketplace, but Bradley, Smart or Crowder have to be traded. Crowder is on a very cheap contract and can play the 4 if they go small. Bradley is a free agent after this year but Boston will have bird rights, Smart is a RFA so any other team can give him a ton and either force Boston to lose him or sign him to more then he probably is worth. Plus Smart is younger so you may be able to get most in return for him.
I think it will come done to AB or Smart getting traded but Im guessing Smart will get more in return. Jackson could survive if the Celtics trade a few pieces for something in return where some money is saved to put them under the cap if DJ is kept. He hasnt played well but he is a cheap option for them to keep around another year.