If nothing else, we can be optimistic. Ive played ffxi since 2003, Played FFXIV since Alpha. There have been Massive changes throughout that time.

Potancy Updates, Maybe putting a Damage received Debuff after a holy cast, since you are literally Searing them with holy light, could even be something as weak at 3% like Bards Requiem.

Cureskin, weaker than AST, maybe 25% of healed amount

Reraise for sure, but that's something that all healers should get.

Could do an ability to mimic the "Boost" spells of 11, where it raises the Jobs "main" stat by 5/10% for 15 seconds, Could link it to the use of a Confession consumption, or an ability on its own.

All of these still fit with the Pure healer role. If anyone played 11, whm was "the" healer. And yet also had several other unique options for damage, until Geo was released.