I feel like most people still having real fun with the game have only been playing it for a few years and are relative newcomers, maybe a little more. All my friends (and past) friends that I know from Vanilla/BC do not enjoy the game any longer, or linger around but are clearly not very invested.
For me the game has been lukewarm since Cataclysm, and that hasn't changed. No expansion, BfA included, has stirred strong emotions in me.