In my opinion, the expansion shouldn't have been a HvA conflict at all. We should've had a much larger focus on Azerite, the new dangers that it was causing to pop up all over the place, resurgent threats from old that were barely holding on getting a massive shot in the arm, things like Ghuun breaking free, and Titan creations going haywire all over the place due to their connection with Azeroth.
Then, when things reach their peak and we're not sure if we can hold the line, Azshara strikes with her armies, forcing us to band together to beat her back, desperately try to keep the planet from dying, and keeping our own nations and peoples from being overwhelmed at the same time.
EDIT: Funnily enough, now would be the perfect time for the 'Mongrel Horde'. Imagine Gnolls, Kobolds, Murlocs, and Troggs banding together with Azerite letting them become real badasses.
That'd be fun.