Richardson is a Very good 3 point shooter and scorer/finisher, and still just 27. He's very underrated, i think. Diaw is pretty bad and Bell has been significantly worse than Diaw this year. It leaves Phoenix a little thin, but makes their overall talent better.
I'm assuming they start Nash, Richardson, Hill, Amare and Shaq giving them two superb outside shooters and 2 great play makers on the court, and one ultra dominant and versatile scorer. They can then use Barbosa and Barnes as shooters off the bench along with Lopez to spell either big man down low.
That's 8 players right there, a pretty good offensive team. Defensively, Bell has really slipped anyway, so they weren't winning any awards there anyway.
If they think they're lacking depth at true PF and the wing and don't want to hand a lot more time to Lopez, I'd try to swing Giddens, Baby, and a second rounder for Lopez.