I don't ask about Pierce b/c that is a forgone conclusion; I mean, they might as well hang his up there now. However, Garnett and Allen are stars, helped the team win a championship, and seem to be loved by everyone.
Boston has a tradition of retiring numbers...a lot of numbers. Even if Ray were to leave/be traded when his contract is up I believe there would be a little debate, but not like with KG.
So suppose (a) *knock on wood* they (Garnett and Allen) win no more championships, have a pretty good season this year, then rapidly decline for the rest of their times in Boston, or (b) they win no more championships, and finish their careers with pretty good stats, or (c) they win at least one more championship would they have their numbers retired in all of these situations, some of them, or none of them? Especially if they end up only playing 3-5 years in Boston.