Additional Variant Jobs?

[Seraphor]

as others have stated the devs have said on numerous occasions that they aren't interested doing another job split like acn/smn/sch again

I'm also surprised they haven't completely separated them yet because behind the scenes over the last two expansions they changed all of SCH abilities that used to be shared/carried over from acn into "unique" sch only variants

The only ability in the sch kit that is still acn/smn/sch is Resurrection
Even the derpy Physick that acn/smn still have sch has it's own unique version of (which really makes me scratch my head as to why they can't make the acn/smn one scale off of int instead of mind but ehhh)

They also stated in a LiveLetter prior to EW that they had strongly considered removing Resurrection from smn but decided to leave it in for now
that's probably the only thing still tethering the jobs together

Personally I think smn should lose it's low level raise and have it replaced with a raise learned at higher level associated with Phoenix for more cohesive identity
could call it Phoenix Pinion for example

They should really just sever the two jobs completely now.
Rename SMN's Resurrection as you say to something more Phoenix inspired.
Rename SCH's Ruin II and Energy Drain.
Have SCH be a classless job that unlocks after the level 30 ARC job quest as it does. It wouldn't be too odd, after all Rogue is a class that doesn't unlock until after level 10.
Grandfather in any players who have already level SCH/SMN (although likely losing intra-level exp similar to when they did the stat squish)

[Seraphor]

Geomancer was their original intention for a WHM offshoot, back before 2.0 was redone, or maybe in it's early planning stages.
Alongside Machinist being the Job evolution of Musketeer, which most likely meant that AST and DRK also had base classes loosely planned. My theory is Astrologian was supposed to be the base class for a Time Mage job, but when they shelved those base class plans they added on the cards mechanics and 'promoted' Astrologian to differentiate it from a full blown Time Mage.

Now that the game has developed and evolved for a decade, Geomancer now is tied to Hingan and Yanxian lore, so it would be odd to split it off from WHM now, the lore just isn't connected anymore.

Necromancer if anything, would be a dps offshoot of WHM, rather than a healer offshoot of BLM. Every existing Necromancer in the game is a former WHM who has bastardised white magic, basically using Raise too late. So it would be a pet based dps job that raises undead minions. But that's not likely to become an actual job.