In principle, and perhaps in need of some work on salary cap details, but why wouldn't the following trade be a possibility - and be beneficial for all teams involved?

This is under the assumption that:

a)the Hawks are unable (for whatever reason) to resign Joe Johnson.
b)the 76ers are looking to rebuild, want to shed salary and need a point guard.

76ers receive: Jose Calderon & Demar Derozan
Hawks receive: Andre Iguodala
Raptors receive: Joe Johnson (hawks sign and trade)

I'm not sure how good my understanding of cap rules is (enter the RR forum), but why wouldn't this work?

-Our defense improves, our offense improves, Bosh gets his wing.
-Johnson gets paid, plays in a big city, on a team with 2 all-stars (both of which could easily start for the East. book it - bosh starts next all star game)
-Hawks save money, adequately deal with Johnson's exit.
-76ers save money, gain excellent prospect and legit PG.