Although it doesn't solve the problem of being insta-50 with a second job, I'd like to see new skills similar to how you (used to) earn PvP skills. I'd rather earn and spend points to raise the ranks of the 1-50 abilities as well as be able to spend points to learn new abilities post-50. It gives you something to work towards instead of having it handed over for little effort, and I think it provides much better expandability than simply raising the level cap. The example that this idea came from: SMN could get access to new egi summons when/shortly after each new primal is released, instead of having to wait for who knows how long for the next level cap increase.
To sort of add to the discussion, I think it would be cool for the third ACN job to be a tank job with non-primal summons such as Good King Moggle Mog and Ultima Weapon. However, as far as I don't have ACN levelled past 15, I couldn't tell how difficult something like tank-swapping would be with a pet, and SE would also need to fix the issue that, as far as I know, other healers have to hard target the summon to use anything directly on it (that is, mouse click/over or tab through targets with appropriate filters set, rather than being able to simply press a function key or cycle up/down with gamepad).
