It’s also all but a given that the expansion will include at least two new jobs.

[Risvertasashi]

What about a samurai that splits into tank and dps jobs like Arcanist does at 30? Have a heavily armored, defensive samurai as a tank and a lighter version with more emphasis on speed or whatever for dps.

They've said a few times that the SCH/SMN split has been very problematic. And, with the balance issues towards the end of ARR, that they couldn't really buff SMN until HW because it would also buff SCH (though they kinda did anyways).

Basically, from a design standpoint, it's so much of a headache that I don't think we're likely to see it again. It's kind of a shame it hasn't been set up in a way that lets them separate out jobs from classes more as the branching thing, to this day, seems to be a strong fantasy among a lot of players, but... it's what we've got, I guess.

tl;dr due to underlying design issues new jobs will probably be jobs only with no base class, like DRK/MCH/AST.

really now?

Well, this whole thread is pretty much wild speculation, so why not!