I honestly can't imagine that grinding on mobs won't be plausible anymore because as long as we're not forgetting this.. FFXI/XIV have always been about leveling on the one character only.
Quests worked for other games because they were static and repeated for each new character/job.
I personally hope all the quests are almost all a one off event for the sake of getting your first or second level 50.
From then on it would make sense story wise that your skills grew into the classes by practicing them in your own time, rather then running back to farmer joe and killing those pesky nutbiters.