I always figured it would go like this:

Red Mage - DPS
Samurai - Tank
Dancer - Healer

With the datamine leaks, it seems that samurai is all but confirmed. It could be tank or dps, although it'd be pretty crazy if they introduced two dps jobs (and only dps). DPS queues would be insane.

I think it'd be more practical if it was 1 DPS and 1 tank. But if they're only making two new jobs, that would leave healer out. And that'd be sorta unfair. Dancer could be the first TP-based healer, and it would definitely make things interesting.

But who knows. I just can't wait for the fanfest and see what exactly is coming. I'm gonna hope for the best, and expect the worst.