Eh, I don't mean to be so harsh. I just hear this complaint ALL THE TIME, but by people that seem not to play most of the game or don't understand how people who don't think like them want to play the game.

IMO, they should make SCH have the DPS kit and pet management (basically return it to SB SCH), AST the buff kit, keep WHM like it is (swap Dia for Ruin 2 and call it a day), Sage heal by doing damage with some kind of DPS rotation (thinking Chloromancer from Rift or something), balance them to all provide the same overall raid damage, then let people play the one they like best.

That's probably the best solution, honestly, as it gives everyone what they want.