Since level cap will most likely hit 70...
1 An end game zone like sky or sea from xi ? something that actually gives us a feeling of accomplishment and to work towards each week vs mindless df grind for 6 months or more ? some kind of pass we have to WORK for after hitting 70 just to enter it ? maybe like a challenge of between normal end game and extreme ? this would give casuals and hardcore something in the middle.
2 Way more side story quests, there simply was not enough, fate grinding and only a few dungeons gets VERY old and boring fast.
3 A second companion, preferably the option to have a retainer like npc to level that takes months to cap or even a merit stat system for ourselves.
4 A much more dangerous open world or the end game zone VERY dangerous that needs at least a full party to explore or do things in.