Whether devs or general players like it or not, everything boils down to the meta. And the meta reads: dps + utility = viability. HPS isn't even a factor really. Why? Because it stands to reason that every healer and encounter must be viable in this regard, otherwise the game would end up completely broken. As long as there are people pushing the meta, there will always be classes in each role that are more or less valued based on what they bring to the table and what the fight to be completed actually needs.

Ast's cards are the highest level of utility possible on a healer. Unless the devs actually break the class's healing capabilities (from what I've read AST healing was dead on arrival in 3.0--that's why buffs started in the first place.), which would not be a solution to anything, AST will always be the most desirable healer to bring long term because they can help make things get cleared faster. A WHM can provide more safety and stability during progression, and I'm not quite sure what SCH brings to the table. But AST has balance and in the viability / desirability formula that's basically a remote with fast forward. Relax: you will survive.