I find it more likely that Bale is going to play the villain, most likely Dario Agger AKA the Minotaur. He's one of the most recent new Thor villains and was created by the same author (Jason Aaron) who introduced Jane Foster Thor, so it would make sense for multiple characters from Aaron's run to be pulled if we already know they're including one aspect.
Agger is the CEO of the Roxxon Energy Corporation and who was kidnapped by pirates as a kid and prayed to a bull statue that lets him transform into a Minotaur when he gets angry (mythical Hulk, basically).
Bale is known for playing psychotic eccentric businessman characters like Bruce Wayne in The Dark Knight Trilogy and Patrick Bateman in American Psycho, so it would be similar to how they type-casted Michael Keaton as Vulture because of his past roles as 1981 Batman and Birdman.
And if you look at the guy's design, Christian Bale can easily pull it off:
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Also, it would be a great change of pace for Thor to fight an Earth-based villain than another god/alien character. Roxxon's whole deal is that they strip mine and pollute the environment, along with creating shady genetic experiments that create characters like Cloak and Dagger. In the recent Thor run leading up to War of the Realms, Agger wants to expand the mining/polluting operation into the Norse realms. And the company has been referenced in small ways in several MCU films and tv shows. And a neat bonus is that the film can tie Valkyrie back into the plot since the Asgardians are based on Earth now rather than coming up with a contrived reason for them to migrate to space again.
I want to believe Marvel Studios is going to do Beta Ray Bill sooner or later, but it would be weird to introduce both him and Jane Foster Thor in the same movie unless they do an after-credits scene or do it near the end like Wonder Woman in BvS, but Beta doesn't have the brand recognition to suspend disbelief for that. And they would need to dedicate some screentime to explaining how another new hammer gets made for him too, although Stormbreaker is supposed to be Beta's hammer and not Thor's new one if we accurately followed the comics. So maybe Thor loses BOTH of his hammers in Love and Thunder? Eh…
But now that I think about it, it would actually be pretty easy for Beta Ray Bill to actually get introduced in a Guardians of the Galaxy film if Thor is part of the cast since it would be easier to connect the tone and cosmic aspects of both series. It could even explain or take advantage of how Guardians 3 got delayed despite originally coming out right after Spider-Man: Far from Home, aside from James Gunn's whole tweet fiasco and temporary firing but supposedly getting rehired behind the scenes months before it was publicly announced.