I think healers are in a decent state right now, and there are already ways to add a new healer.
The balance thing is overblown. Yes, WHM has a DPS issue, but as far as healing goes, everyone already has enough of that. I don't want to see many or any new healing spells. Anything they add should be done with traits, in my opinion.
WHM's kit is more or less fine as is (minus lilies, and they could maybe use a cooldown-based oGCD party shield or damage reducer), but if they want to boost it's DPS, they can simply raise it's potencies, and I suppose a 1.5s Stone cast wouldn't hurt either. More than that isn't necessary. I get the distinct impression that most people who complain about WHM's lack of mobility don't know and/or don't want to to learn how to play a low-mobility class. BLM has insane damage output, and this is furthered when the player in question knows how to play to minimize movement. Yes, they have Triplecast and the like, but those aren't even needed as often as you think.
Perfect balance is impossible to attain. While WHM obviously gets the short end of the stick right now, that doesn't make it a bad job. If they just flat out boost it's damage output to put it on par with other classes, that would be fine by me.
As for healers in general, I think it's about time we stop getting our hands held and go back to some more challenging content that demands more healing time. If you go back and play old content on MinIL, you will see just how big a difference there is. Basic tank upkeep is actually a fairly active job, and dangerous damage spikes aren't announced by a super long cast bar every time.
But for everyone wanting a challenge, I would also suggest solo healing. Remember, healer is a touchy job. If the party has a bad healer, the fight will wipe without fail. So they can't make it so hard that weaker players can't handle it at all. Instead, they've focused on giving us more than enough tools, then asked the experienced players to have fun by optimizing. And I have no problem with that approach, honestly. Challenge is something people can make for themselves as well.