If they can get Bosh for Amare, you do that deal. Bosh would be even better with Nash running the show for him, and he's absolutely a franchise cornerstone. Much less of a headcase than Amare.
From Toronto's perspective, if Bosh's people HAVE told Conangelo that he's not going to re-sign in 2010, Amare's probably their best-case in terms of return compensation for a trade. It's a lot better than expiring contracts and draft picks.
If Phoenix cannot get someone like Bosh for Amare, they need to seriously think about where the team is going and who's untouchable (read: Nash). Add Bosh to Nash/Shaq/Richardson, you're got a potent combo that should be able to play both uptempo and halfcourt, and MIGHT be improved enough on defense (maybe have to do another deal; Barbosa for a defender) to do something good in the playoffs. Not better than the Spurs, not better than the Lakers, but good enough to get at least into the second round.
If they can't get someone like Bosh, they need to think about blowing the whole [dang] thing up, because it's not working right now. Nash still has trade value, if they can'r bring back another impact player for Amare they need to think about getting value for Nash while they can.