10 TRAGIC Predictions For Avengers 4
8. The Second Fall Of Asgard
When Thor: Ragnarok initially ended, there was some hope for Asgard and its people. Thor had taken his seat on the (temporary) throne in the wake of his homeworld's destruction and the agenda was to resettle the Asgardians on Earth. But then Thanos turned up and killed half of the survivors, scattering the rest in escape pods and trying to kill Loki, Heimdall and Thor. He obviously almost succeeded.
You'd like to think that the survivors - led by Valkyrie and perhaps Korg and Miek - might still get a chance to resettle (assuming even more of them weren't killed by the snap, which is horribly possible) in a New Asgard. But then, there's no way Valkyrie wouldn't find a way to join Thor in battle against Thanos if she realises the odds standing between the Avengers and defeating the Mad Titan.
If it's true that Marvel have no plans to make Thor 4, then the easiest way to close that book is to kill the Asgardian off AND also resolve the Asgard story. And the only way to do that within Avengers 4 is to kill all of the survivors and make a New Asgard a redundant concept. It might seem harsh, but it's one of those loose ends that needs to be addressed one way or another and finality is an easier thing to fit in an already busy plot than a hint of continuation.