As far as I can tell, there isn't a heck of a lot they can do. I'm not trying to be a jerk... it's just the truth. No miracle trade is going to happen.
Presuming KG retires leaving us with nothing...
We still don't have cap room.
Pierce is too old to have real trade value.
Rondo is a Top-10 PG coming off major surgery and plays a position that 80% of the league has covered fairly well... could we get a lotto pick and expiring contract for him? Maybe.
Green is still seen as overpaid by some. Bass, Lee and Terry are all borderline "bad" contracts at this point.
The pessimists won the debate on Avery Bradley. He's too small to play SG, very weak offensively... inept at running an offense... essentially nothing more than a defensive role player who might not even be a starter... and most of his defensive success comes from his hyper-aggressive defensive effort... which leaves him useless on the offensive end. Some day he'll have to ease up on the defense to bring some balance to his game... and then you're left with an undersized guard who can't shoot or pass. Can't see him fetching much of anything.
Sully was a late 1st rounder and he's coming off surgery. He's not getting you much.
Fab Melo will probably be out of the league in a couple years.
That pretty much covers it.
Realistically, I see us getting very little for our assets. No superstars to be had for what we're offering. And without KG, this team is probably on the verge of the lotto already. So best plan of action is to probably find some way to dump the bad contracts, get draft picks for whoever can fetch them (Rondo and Green, maybe)... Go "Full-Blown Tank Mode" and hope we luck out in the 2014 draft (Andrew Wiggins) or free up enough cap room to make an ill-fated run at some legit stars. You build through the draft... pick young guys with potential. In 5-10 years maybe they pan out and you have a contender.
It's basically 1995 right now. We'll hope for the best, but if things went the way they went last time, we're not sniffing contention again for another 12 years.