How would they even make another healer job though?

[Berteaux_Braumegain]

Maybe a greater focus on AoE placement heals/ shields / buffs? If the next healer is geomancer, it could be like we are casting enchantments on the land itself. Think of those totems the enemies use in Wanderer's Palace (Hard).

From what I've seen in the Astrologian quests, Geomancer is just reskinned White Mage in XIV. I'd say that an item based healer would probably be the next logical step. Given Alchemist is already being used, call it Apothecary (ala Octopath Traveler) or Salve-maker (ala Bravely Default).

Healer but with a rifle

I think there's a job in TA2 called Canonneer that works like that.