I recall Yoshi-P saying he wanted to implement an Onmyouji caster type of class which also deals with divination, cosmology and magic, but I don't see what they'd want to take from AST at this point (though, Square has been on a roll with making confusing decisions).
It might've been scrapped though since they're more occultish compared to AST, and they might've wanted it to be a dot-based cursing/debuffing type of class in place of SMN.

If there IS a new caster, I wouldn't be surprised if they ended up stripping RDM instead and repurposing some part of their kit for the new class, but it's not something I look forward to anymore as they would end up not being distinguishable from the other casters (except our BLM overlords).

Look at how RPR turned out: it's a simplified version of DRG.
Sage is SCH without a healbot and buffs.

I'd rather them funnel the labor and budget of creating new jobs into expanding their design team since it's glaringly obvious they don't really care about expanding healer roles in this game.
We know there's a DRG rework that's gearing up for 7.0 too. I'm more curious how they're going to handle THAT.