It might seem unlikely to construct a solo movie for Hela, even if Cate Blanchette came back to reprise the role. But if you think about it there was a lot mentioned in Thor: Ragnarok that didn’t receive a lot depth and could possibly be used to create this movie. Of course it would require Anthony Hopkins, or a convincing stand-in, to take the role of Odin, as she is his first-born and as a result they were apparently a genuine terror to many civilizations. If you don’t recall in the last Thor movie, Hela actually boasted to her younger brother about how they drowned entire worlds in blood, so to speak.
This would be a pre-Thor movie obviously since Hela and Thor knew nothing about each other until Ragnarok, so it stands to reason that Odin didn’t have Thor until he was well and done with his conquering ways. For some people thinking of Odin as murderous and as the type that would gladly wipe out entire civilizations is hard to hard to fathom since the movies have made him into a more benevolent king. But if you read simple mythology or even the comic books you’d find that Odin was not always the calm, rational-minded individual that Hopkins portrays. Instead he was known at times to be cruel, capricious, and even more vicious than Hela. But changing the narrative for the Thor movies was more in keeping with the ideals that Disney and the MCU wanted and so Odin was only ever shown to be savage when he absolutely had to be, which wasn’t often. Near the end, Odin was fading fast and was calm and reflective, not war-like and combative. Hela on the other hand is quite the dominating force and for good reason. When Odin couldn’t control her any longer he cast her out, banishing her to the netherworld where she would languish until his demise.
You can imagine that she’d feel a certain way about that, especially since he not only denied her the birthright that was hers when he passed, but also because he essentially replaced her with Thor and then Loki. He covered up everything that they’d done together and in a way rewrote history so that people would forget about the past just enough to believe that Asgard was a truly wondrous place and wasn’t built on a mountain of skulls and an ocean of blood. Hela’s story might be a little over the top but at the very least it has the advantage of being the dark, gritty truth behind the pleasing facade that Odin built to glorify the life he had chosen after her exile.
This movie could easily work so long as the needed actors were brought back. In following with MCU tradition however it would need to pull from recognized mythology in order to really gain any ground, and would then need to stick to the story as much as possible in order to follow through. There’s no telling if we’ll ever see this kind of movie, but it would be fun to see how Hela started out.