FFXIV should embrace pre patches, during which they release new jobs and races (If the expansion has one).

I would daresay to say release all battle changes as well (of course, with the current expansion level cap), but that would be too much.

This approach will allow people to tinker around with new jobs in preparation, and most importantly to dive into the new expansion with the new jobs.
Thus avoiding the situation where the player is forced to grind for 2-3 days straight for that 10 levels.