Class order halls and class quest-lines should come back next expansion because they made leveling new alts more fun.

Edit:To elaborate on this now that I have more time, leveling in Legion was a lot more exciting for me because it allowed me to view the war from multiple different perspectives, and showed how each separate class hall contributed to the war in their own way.It would have been cool in BFA to see the effect the war had on the class halls and the people in them. To see the effect that the fall of Teldrassil would have on the Night Elven demon hunters, and the effect the deaths of loved ones would have on the people who were supposed to be teaming up to eliminate old god threats.