I don't propose to keep WHM exactly the same, but simply not to alter it too much, so it won't alienate casuals, and then bring back AST and SCH to former glory. I fully understand that this is not ideal, however, it is realistic. How many times in this game's history did they make job harder and more complex, instead of easier and more brain dead? Which is why I think it's okay to have this sacrificial lamb, that people dissatisfied with the potential changes can turn to.
Yes, my idea is essentially negotiating, again, it's not ideal, but it's more realistic. There are casuals, which do indeed like playing healers for their simplicity. Some people are just fine with 1211111, and even though my inner gamer would want these people to wake up and put more effort into their gameplay, that's unrealistic, this game does have a lot of these people, and we know from the past that devs are afraid of the casuals and wouldn't want to go against them.
As for implementation details, there's a lot of theory crafting, with making GCD heals be worth it, making healers actually heal and so on. You could make AST cards GCD, but next malefic will deal 2x damage, Adlo could deal damage if it bursts, or refund you gauge when it doesn't, whatever, there's lot of options how you could fix healers. But I'm not really qualified for this, and jumping straight into details when we don't know if SE will even bother doing something is not my forte.
I think we discussed this enough in that SMN thread. It's complex set of issues, it's not just about damage, it's also about difficulty (both general and encounter-specific), utility and tax for it, mobility, community's perception and many more.
I can remove my signature, and you can slowly start restoring your reputation. But if you keep making these walls of texts, making bad arguments and dying on the most stupid of hills just so you seem right, it won't help.