I suppose there really are two questions here.
The first is whether Rondo is healthy. I haven't seen him play yet (and obviously his minutes are down) but his numbers look down a bit, and his shooting is terrible. Could be rust, could be the effect of suddenly being the #1 offensive option (his FGAs are way up per minute), so that's not the kiss of death. But before selling the farm, I want to know that he's going to be the player he was before the injury.
The second is what we could possibly sell to get him. Salary matching in and of itself won't be a problem - we can get away with sending the Celtics only about $7M if it's for Rondo straight up. But we'll take DMC and Gay off the table, and we don't have a first-rounder to offer them. We could design numerous "option-to-swap" scenarios, but those aren't terribly big incentives if the trade that generates them makes the trading partner into a top-10 team. For instance, we could give them the option to swap for each of the next three years (subject to Chicago not getting the pick), and with them rebuilding and us in the playoffs, never actually convey anything. So you figure IT and Ben would have to go, and then...DWill? Would the Celtics actually go for IT/Ben/DWill with no guaranteed picks? I don't know.
Still, that trade would only give us one year. This year is already burned, we are just too far out to back into the playoffs. Assuming Gay does not opt out, after our first year I the playoffs (2014-2015) we would have to resign both Rondo and Gay. We'd have the cap space to do it, but we'd have to actually make sure they stick around. Would we have to put out three max contracts to keep that core? And would that be worth it?
But it definitely is intriguing.