MCU: Why Natalie Portman Is Becoming Female Thor
3. Jane's Worthiness
The second thing that needs to happen is that Jane Foster needs to prove herself worthy. Or so you'd think. In actual fact, there are two ways Taika Waititi can get round that. The first is to have the Jane Foster who appears in Love & Thunder be from the multiverse as well as her version of Mjolnir.
In the comics, there's a fundamental conflict between Odinson and the Female Thor as she refuses to reveal who she is to preserve Thor's feelings. What if the Multiverse opening in Doctor Strange (through some unforeseen rift event) brings a Thor from another world (just as Mysterio claimed to be) and we see a conflict between Chris Hemsworth's Thor and the new multiverse Thor that mirrors the mystery of the comics?
That would give us a tie-in to the What If...? animated series - and already we know how Marvel likes to employ running themes across multiple projects - and would also tie in to the strange idea introduced in Endgame that Thor would simply abandon his post to Valkyrie because he no longer wanted to be king of Asgard. That unsatisfying to his entire arc would make a lot more sense if the next step in the arc was him having to face the consequences of not only him not being Thor, but also of SOMEONE ELSE being it in his place.
So in that respect, having a mysterious Thor in place to fight with him to literally personify that conflict - as a sort of A Christmas Carol set-up only with Foster's Thor in place of the three ghosts and Jacob Marley. Or a It's A Wonderful Life deal whereby Thor's shown what his life and Asgard would be without him. Sure, it comes at a cost of Valkyrie's worthiness to be the king of Asgard, slightly, but Asgard needs both a ruler and a protector in this MCU, so it could be done.
Alternatively, Jane doesn't necessarily need to prove herself worthy in the same way Thor did and Captain America did. Assuming she's not just going to be worthy as a starting point, it's possible for the ruler of Asgard to grant the possession of Mjolnir to its owner in the MCU. Odin took it away from Thor and could grant it again. So, with Valkyrie in power, you have to imagine that she would be capable of making Jame Foster the Goddess Of Thunder.
For that to happen, they'd have to meet, you'd suspect, but then Jane Foster should be counted as a hero in Asgard for her role in helping Thor protect the realm, particularly in The Dark World. If she was in danger - as she would be if she was terminally ill, for instance - the surviving Asgardians might rally around her and demand Valkyrie use her powers to save her. And that would go doubly if the illness in Jane was linked to Asgard specifically. But how could that happen?