PvE is definitely in a need of revamp of sorts. There is no any real highest of the high level PvE content outside of E4 rematches that are not rewarding in the slightest. We already have a bunch of custom battle mechanics for event (and story) boss(es), I don't see a reason why it wouldn't be possible to create new, regular content using a similar approach. Either way, something new to do PvE side would be not only refreshing, but needed