Short of getting a third difficulty, I don't see a path to raid content that doesn't just boil everyone down to a DPS. Healers are basically DPS with healing spells, Tanks are DPS with defensive CDs, etc. Even if they nerf the hell out of tank and healer DPS in SB, the choices are still either 'use spare GCDs to do nothing' or 'use spare GCDs to do pitiable damage.'The entire game and combat system is built around these super binary spike damage pass/fails--Did you use a CD before the tank buster? Did you tank swap? etc. You either pass and live or fail and die or they tune everything so low that you just power through it, and even in that case it amounts to one or two extra heal casts and then business as usual.
It doesn't help that probably the most healing-intensive mechanic XIV ever saw was Nisi, which basically nobody bothered with doing. Elysium had an Excel spreadsheet breaking the back half of A4S into GCD by GCD sequencing of what had to happen when, when was safe to pass, when a Nisi tick was likely to coincide with Mortal Rev, whatever. It didn't necessarily dominate literally every single GCD for healers, but it has to be the most insane thing the game ever did. Only they stuck it in the back half of an overall bad fight, combined it with some crazy HP check requirements, and then put Living Liquid in between everyone and even starting the fight. And then Lucrezia intro'd sac strat and everyone just cheesed. Which is a pity, because there are aspects of Nisi that could have been kind of cool if the implementation hadn't been hot garbage in the Manipulator dumpster fire.
So I doubt we'd see something as healing-intensive as that again; more likely we'll just keep getting stuff like the Void Puddle/Holy Bleed/Communion/Incinerating Heat fiesta at the end of A12S, or Photon during Pyretic into Whirlwind in A11s. Short bursts of focused healing, but they make up the minority of the fight so that they can just be tackled as isolated incidents in a sea of fuck-all to do.
The healer DPS focus in raids is generally just to make up for DPS jobs' damage outputs being sub-par anyway (or for Sarc to let me die while he focus on max deeps), so I'd be fine if they purposely made those fights more healing-intensive to help refocus on putting the main DPS pressure on the actual DPS jobs.
We're coming off of Creator which was pretty straightforward tuned for subpar DPS with 0 damage healers, so I dunno how true that is.