The Avengers: Endgame that his popularity skyrocketed.
While the rest of the original Avengers are either dead or on the verge of retiring from being a superhero, Thor still has a future in the MCU. He's set to be the lead of rumors of Beta Ray Bill making an appearance. Both characters could take Thor's place after Phase 4, but which one will?
If the MCU chooses either Jane or Beta Ray Bill to be the new Thor in the MCU, Jane is arguably the more logical choice. The return of Natalie Portman is significant after her prior experience with the franchise, and the Oscar-winning actress could lead a franchise of her own in the future. This would require Portman to sign on for multiple more movies (which isn't confirmed), but Jane has immense potential as the next Thor in the MCU. Her battle with breast cancer and the adverse effects being Thor has on her recovery is a fascinating story. Plus, Jane is powerful enough to be a heavy-hitter in the MCU, similar to Thor, while also potentially signaling the return of Mjolnir.
Beta Ray Bill would make for an excellent Thor replacement in the MCU, but it is a bit more difficult to picture him as a franchise lead. The Korbonite warrior will likely be a completely CGI character, and Marvel has so far yet to make a non-human looking character the lead of a franchise. This wouldn't mean that Beta Ray Bill's future in the MCU is non-existent, though, assuming he does debut in Thor: Love and Thunder. His place could be on a new Guardians of the Galaxy team while Jane's Thor also protects the galaxy and Earth.
Even though both Jane Foster and Beta Ray Bill could work as Thor's replacement, there is also a chance that neither of them will take his place. It is unknown how long Hemsworth plans to be part of the MCU, but his excitement for the character was reinvigorated thanks to Taika Waititi's comedic direction. Hemsworth's Thor might not get another trilogy of films at this point, but we can't count out the chance he remains part of the MCU beyond Phase 4.
Whenever Thor's time in the MCU does come to an end, that could be when his replacement becomes clear. The combination of Jane's story and Portman gives her a potential advantage in taking that place, but its possible Marvel doesn't try to replace Thor with one single character. Jane could take on the Thor name, Beta Ray Bill could receive Stormbreaker, and Valkyrie could continue ruling over Asgard. This would split Thor's responsibility between multiple great characters and elevate all of their MCU futures.
