AST+SCH is more effective than AST+WHM from a dps perspective (which is all that really matters), if the
leaderboad is any indication.
WHM+AST can be done, but you have to forgo the fairy and the reliable dps of the SCH, which is why the more difficult turns (A3S and A4S) typically have AST+SCH. The best combo is still WHM+SCH according to most raiders because of how well they work togheter, but AST can now substitute the WHM as the main healer thanks to the recent buffs. And I don't think AST will be nerfed, but who knows...you kept saying that the AST was fine and didn't need any buff, so I can't really take you seriously, sorry.