I continue to think everyone is overreacting to the "post Big Three era."
The only reason we turned into a terrible team is because Danny Ainge inherited a truly woeful team. Believe it or not, it takes time to rebuild, and that's exactly what Ainge had to do. He could have pulled the trigger on guys like Baron Davis, but he held his trade chips until he thought he could obtain all the pieces.
The rebuilding stage would have continued into 2007-08 had we landed Oden or Durant obviously, but Ainge pushed all in once we crapped out in the lottery.
Who would have thought we would go from a 24-win team to 66-win champions overnight?
I trust Ainge. I think he will continue to draft young guys with high upside with an eye on the future - as opposed to drafting lower potential, help-now guys. He is not afraid to trade any player IMO (traded 'Toine within months of being hired), so using expiring contracts (except perhaps Pierce) to land younger players is something he will explore if this team isn't at an elite level.
Will they be contenders for the next 12 seasons? I doubt it, but what team will be? But I do expect them to be a playoff team for the next 6-8 because of Ainge and Rondo alone. Add in the MLE/LLE signings, smart drafting, good role players, and veteran leadership, and this team won't be a "20-35 win" team for the foreseeable future.
Believing things will get "ugly" once the Big Three retire is just being pessimistic. There is a BIG difference between rebuilding a Pitino-assembled team who peaked at an ECF appearance and rebuilding a championship team that got old.
I'm not gonna fret over the future when the here and now looks bright.