I think the plan is to go after the melo this off-season. He and Rondo would be a legit 1 2 punch. Don't we have money to offer a max this off-season?
If the plan is to go after Melo, the Celtics would probably be more attractive if they made the playoffs.
The Celtics could probably clear the cap space to offer Melo a huge contract. The team would have to give another team first round picks to take on contracts such as Bass and Lee in the same way that Golden State used picks to clear space to have a shot at Dwight Howard and to be able to threaten to sign Iguadala outright so that Denver had to agree to a sign-and-trade to salvage something.
Maybe Melo makes it obvious he wants to leave because the Knicks are hopeless and you could get some ridiculously huge trade such as Carmelo Anthony in a sign-and-trade and Tyson Chandler for Green, Faverani, Bass, Lee, the unguaranteed contract of Bogans, and 3 or 4 first-round picks.
The Celtics could look like:
Chandler
Sullinger
Anthony
Bradley
Rondo
with a bench including Wallace, Olynyk, and Pressey (although I suspect the Knicks would press hard to get either Sullinger or Olynyk in any deal). The Celtics may end up far enough under the apron to use the full MLE. Ship out enough salary early enough in the off-season and they may even be able to take the contracts of some good but possibly overpaid players in a salary dump by using their trade exception. Colton Iverson might be ready to be a third-string center. You could get some ring-hunter for the veteran's minimum and some useful players may find themselves settling for the minimum in August or September when free agent money dries up.