I have to admit that I am a bit disappointed with endgame in Heavensward. It is not bad, but it brings nothing new.
It is hard to come with some new suggestion about endgame content because every time I am trying to come out with something fun, there is that big wall called "server data limit". There are good ideas in some content in this game but in my opinion it always lacks depth.
I would like to see revamped PvP, some large scale community events (not these jokes called FATEs) and stuff with more mechanics than kill, collect, bring.. maybe the ability to build small castle with my FC in instance and then defend it every day against mobs and bosses. But that is impossible while we cannot even give every player a house..