I was thinking about Dragonflight's story, and I recall the announcement event spoke that the Dragon Isles would be awakened and the dragonflights called again to protect Azeroth... but protect it from who and/or what? I noticed little has been said about threats. Nothing at all about the "Big Bad".
So... how about we try to hypothesize who or what is going to be the "Big Bad" of the Dragonflight's expansion, but let's try our best to not "invent a Jailer". In other words, let's try to stick to current canon and use the existing groups, races and characters that currently exist (or have existed) as much as possible and avoid creating entire new groups and/or villains that need a lot of the lore twisted and bent to be able to fit in.
For example: would the Twilight Hammer make a comeback and attempt to continue Deathwing's work? Maybe the Void Lords decide to take a more active role in attacking the cosmos? Maybe Sinestra is still alive and was preparing an army of Twilight Dragons? Or... the Infinite Dragonflight is going to make a big play?
So, with that said: what are your predictions about who or what is going to be "Big Bad" of the Dragonflight expansion? Against who or what do you think the dragons are being summoned to protect Azeroth?