Not that I disagree with you at all but according to one interview the people asked Yoshi-P about how he mentioned more "Jobs" as opposed to more "classes" and his response was "You have a very good ear for this."
So from this we can at least assume that they will be "Jobs" and would have to branch off from the original classes. OF course this doesn't mean they aren't capable of revamping skills to fit both branches.
again, just speculation on my part.