I think the best bet, though I doubt this will be done by Heavensward, is to just revamp the base classes into full-fledged jobs of their own. They can share similar bases to their advanced jobs, but develop into something more unique post-30. This way they don't have to redo or gut a whole bunch of lore.

I'd like cross class skills to be revamped though. The restrictions really need to be removed. It's one of the only possibilities for variation we have on our character and it's very Final Fantasy. I really would rather the system be given a chance to shine before everyone considers throwing the Squire out with the bathwater.