Rondo is the face of the Celtics. You only trade him for Chris Paul/Durant/LeBron, but that's not going to happen.
A team without KG and Pierce is bad enough to get a top 5-10 pick. Even if the Celtics tried to tank like they were the Bobcats, like in 2007 and 1997, the ping pong balls won't fall their way. So a top-5 or even top-10 is bad/good enough.
They can pull a D-Rose with Rondo (and Sully), so that won't be a problem. The real problem is what can you get from Pierce/KG. KG in a trade&retire could bring a future pick and an expiring horrible contract (i.e. Turkoglu), so you don't have to worry for him to not suck and ruin the tank plan. KG files retirement and can come back as an assistant coach. Orlando saves money AND cap space, Turkoglu expires in 2014 and you can use his expiring contract and/or the pick to improve your chances in the 2014 draft.
PP+Bass for Boozer+Rip Hamilton+Bobcats 2014 first rounder. Chicago starts Gibson, saves one year of Boozer's contract, and gets a 6th man to win it all in Pierce and a great backup in Bass. Fair trade, although I'd hate to see the Captain in red. The Bobcats pick is top-10 protected in 2014, top-8 in 2015 and unprotected in 2016
Boozer doesn't give you enough to not suck (Rondo wouldn't be playing), and you can package him later with a young player and a pick to get an All Star in return.
You keep Rondo and Green, unless you get something really good for them. Sully and Bradley are keepers while you build their trade value (or they become building blocks), and so it goes for the other young kids. Lee and Terry won't be easy to move, but if you get the right offer, you take expirings and picks.
Cap flexibility is the key, and developing/adquiring assets is the goal.