Well, it's not much to go on, but on one of SE's sites that talked about what'd be coming in Stormblood, when they mentioned what jobs were coming, they worded it in such a way that suggests we may get at least 3, if not more.

Then again, it could be a translation error, because it was something along the lines of, "Featuring Red Mage, and other new jobs."

"Other new jobS."

I'm curious, to say the least.