If Arcanist could do it...

[EmmetOtter]

Given how the game works right now, where your stats come from your gear and players have a separate gear set for each of their jobs (with different materia at least), I don't see how "balance" is still a problem. The only truly unique thing is your job's soul gem.

I could see this being a common player objection, "I want to be a Green Mage, but I don't want to Marauder not even for a mere 30 levels". The easiest way to avoid that is to make "Green Mage" just another job like Samurai, Machinist, Dancer, etc... that anyone can switch to.

[Bright-Flower]

Arcanist was designed to split and even then it's been a headache for SE and they've tried to differentiate summoner and scholar more over time and regret doing it the way they did.

Taking classes that were NOT designed to branch like this and trying to force it on would just be clunky and add problems, when they could just continue the current trend of releasing new jobs not tied to classes.