When level cap raises it does make sense to add in a quest or some kind of challenge. I did like the level caps back in the day, they were fun and something different to do (also designed to make you explore places you normally have no reason to beyond missions.)

I don't think we'll have any mentor type fights since in our final AF quest we generally fought someone who has a significance to us in a way, i.e WAR/DRG/MNK final fights. I hope it's more along the lines of level 55 and 96+ cap of some kind, exploring a far away land and fighting monsters to gain fragments to prove your worth.