If he doesn't retire I think Ray stays, Bass comes back and we are able to add one good rotation player to the mix via free agency. The team improves and competes for a title next year.
If he does retire, I think we save the cap space until next year. In which case our defense will plummet. Rondo and Bradley will continue to get better and they are still a playoff team. However, with a big rotation of Bass, Wilcox, Green, Stiemsma, JJJ and a rookie (Nicholson, Melo, or White probably) we won't be able to do much damage in the playoffs.