As levels increase, there will be more differentiation between jobs and their base classes. I assume there won't be a lot of new additions to classes when levels increase, possibly additional traits or something of the like. Most of the new skills will come from jobs.

As for not using classes in the current game, they will most likely be what is used in PvP. Having 10 cross class abilities of your choice will make for some interesting PvP battles and actually add some diversity to characters.