By now we all know that there are going to be some major casualties in the Marvel Cinematic Universe following the events which are going to take place in Avengers: Infinity War and Avengers 4. There are a number of the top stars in the Marvel Cinematic Universe who will see their contracts coming to an end, which has led to many suggesting that we will see them being called off or replaced.
It was recently suggested that we are going to get to see Gwyneth Paltrow as Pepper Potts suiting up as Rescue, which has led many to suggest that we could also see some other female characters in the MCU taking over from the men in their life. One such rumour has claimed that we could well get to see Natalie Portman making a return as Jane Foster in the near future, even going as far as to suggest she could also become Thor the Goddess of Thunder.
These rumours are currently nothing more than that and it is just the actual fans of the comic books pointing out something that actually happens in the comic books. With Jane Foster being the ex-girlfriend of Thor in the movies, much like she becomes in the comic books, and with Chris Hemsworth's contract coming to an end, it would definitely be interesting to see if Marvel Studios would actually go down this route.
With that said, Natalie Portman has previously said that she has no plans to return to the Marvel Cinematic Universe as Jane Foster, with Marvel not being in touch with her about any new plans to bring the character back, so it looks unlikely that it will actually happen, but stranger things have definitely happened.