I'm incredibly exhausted right now, so this won't be quite the post that I have in my mind. However, I feel it's pertinent to get this message out there. Do not let the voices of other others opinions corrupt your expectations for the coming expansion. Expect a fun interesting new main story quest and additional classes with a new combat system that may turn out to be better than the current one.

You will enjoy the expansion so much more if you don't read about it constantly or try and debate and uncover things. The people who tend to try and uncover every stone before they're laid also tend to be the ones least content with the additions to the game. I used to do this for other games namely WoW and I was incredibly disappointed with MoP & WoD. Going into Legion blind was the best decision I ever made.

Just enjoy the game, and don't spend too much time on deliberating future content or you just wind up setting yourself up for disappointment by having expectations too high.