Honestly, it would be derivative at this point.
Santa Monica has just performed one of the best soft reboots ever in gaming and produced a masterpiece. Thor is pretty much part of this universe and has been built up as a drunkard with nothing but lust for blood and combat, a pretty good depiction of aesir gods, not the marvel shyt, and he's pretty much a villain that we'll face at some point. Mimir forewarns that'll be a major obstacle. I'm saying that to say, why would they make a game with/about Thor? just so people can experience Mjolnir? makes no sense, especially when Mjolnir is undoubtedly more limited than the Leviathan axe and is merely used as a conduit for Thor's power.
and if you were suggesting another studio to do it, I don't think many studios have the know how/technical expertise to create Mjolnir as an accomplished combat tool as Santa Monica did with Leviathan. From the animations, to weight and feel, to moves that are in synergy with its ice/frost elemental nature. The combat system in this game is crazy. I mean, and then there's technical aspects like returning on call, cutting through and holding to surfaces and the distance you can put between yourself and the axe and varied response and return times depending on said distance. Its like, if other studios could, they would have. This game is not only groundbreaking in regards to how good it is as a playable experience, it is also a technical marvel. I remember back in the days me and my nikkas would ask why Sony ain't got a title like Super Smash Bros and then that All Star Battle Royale shyt happened and we realized why. It wasn't the worst game, it just wasn't Super Smash Bros, and even if it had a bigger budget and given to a more reputable development studio, chances are it still wouldn't touch Super Smash Bros cause Nintendo got the recipe for that (not to say that derivatives can't carve their own lane, it happens sometimes).
I'm saying all that to say, Marvel holds the rights and licenses to the pop culture comic depiction of Thor, and outside of that, Santa Monica already has their own version of Thor in this very same GoW universe, and an objectively superior weapon to Mjolnir in the Leviathan axe (this is not debatable just by the nature of the Leviathan being able to do more than just smashing really hard or conducing electricity), so I don't see them going out of their way to make a Thor game, and I don't believe other studios would be able to match what they did here, not currently at least.
although we haven't seen Asgard yet.
