Specifically the bolded part, Dungeons are the perfect way around this. By incrementally increasing the healing requirements per dungeon you incrementally boost their ability to heal going forward.
It'd be hard to get the scales to balance properly, but if they did it correctly the result would be more Healers at level cap better able to deal with higher frequencies of damage.
Ironically, I think its the 'vets' that would struggle more with increased healing requirements. Evidenced by a video I saw from the media tour of an AST in the dungeon. Incoming damage was fairly consistent on the Tank, yet the Paladin was frequently dipping to 20%~ and even died on a small trash pull at one point.
So I rewatched it and paid attention to the cast bar and sure enough, The Tank was sub 50% hp with 7 mobs beating his face in and the Healer is happily spamming Gravity with no concern for the Tank that was about to kick the bucket.
The irony is that Healers have been doing this since 2.0. People like to dress up SCH dps like its something special, but the reality is that it was DoT+DoT+Ruin spam from launch. Whee, such complexity. Dropping AoWs between Heals will add some interactivity on trash packs, IMO.
WHM was the same. When AST came out, it was also the same. Especially back when they could all use Aero.
Even right now on live, a WHM gets its first damage skills at 1 and 4 and doesn't get A3 till 58. That's 58 levels of 1 DoT and 1 Nuke. No different to what ShB is giving us.
SCH isn't much better, getting its 2 DoTs and nuke by level 10 and then simply never getting another rotational damage skill. ED is damage yes, But due to Aetherflow, its basically a short cooldown oGCD not much different to Assize.
SCH losing its second DoT was a bit surprising, but ultimately won't make a difference in how the SCH plays. You just use Broil where you would have used that Miasma. Healer dps has never been interesting. Not in ARR, HW or SB. Its literally going to be more of the same in ShB.
I was genuinely surprised to see WHM get a new damage spell. Though Misery seems to their answer to CS and Cards.