This is, to a degree, some justification to claiming that we will still be at 5 Job abilities on ARR release. Obviously, without
the final wordtvtropes warning, it's too early to tell. However, the fact that the achievements for completing the Job quest lines are not going away strongly implies to me that they are not going to make any major changes to those quests in ARR. Now, that doesn't mean they can't tack on a few extra quests at the end; though I think that would be somewhat forced.
Certainly, I hope that there are more abilities to play, with for classes and jobs, but until we know more, it's best to assume that things will not change too much.