Spoilers below for Thor #2 by Donny Cates, Nic Klein, and Matt Wilson.
In the first issue of Thor, the Black Winter was teased as a catastrophic new threat. The Black Winter is so powerful it took down Galactus, barely keeping the Devourer of Worlds alive. The Black Winter is set to wipe out something even bigger than Galactus - the entire DC Universe.
In Thor #1, Galactus falls out of the stars and crashes down on Asgard, causing severe damage upon impact. Once the weakened giant gathers himself, he tells Thor that he's the only one who can stop the Star Plague - otherwise known as The Black Winter. The Black Winter is described as "... the end. Of everything." It's clear the Black Winter is not just a huge threat, but something that can annihilate whatever comes in its path. It's why Galactus makes the God of Thunder his new Herald.
Thor writer Donny Cates shared a preview of his and Nic Klein's upcoming Thor #2. The first look showcased a universe being completely evaporated by the Black Winter. It kills everything it touches, almost in the same way as Thanos' snap. It eventually engulfs the universe's Earth, but not before it's hinted that the Black Winter is actually taking out the DC Universe.
In the preview, the question is asked as people are killed "will you scream to your gods?" cutting to what appears to be Superman flying by the Daily Planet as the Earth is getting consumed. Then it mentions "a sun god," "a god of emerald light," and "a god of the ocean. Of speed. Of strength." While it doesn't say the heroes by name, it's clear it's referencing Superman, the Green Lantern, Aquaman, The Flash and Wonder Woman. If the references weren't clear enough, the scene also shows the speed trails, including The Flash's iconic lightning.
Cates couldn't reference the heroes by name since they're obviously owned by DC Comics, but it's a more than subtle nod showing just how powerful the Black Winter is. It destroyed a world with superheroes with relative ease. The people's cries for help could not overcome the plague the Black Winter brought. It's a brilliant way to show just how much of an uphill battle Thor is against as the new Herald of Galactus.
If there's one trait Cates is known for in his writing is his ability to tell huge stories that break the status quo. Thor #1 delivered that and it appears Thor #2 is going to be just as big. The Black Winter is coming and the only one who can stop it is Thor - but the question remains, is that even possible?