When Avengers 4 premieres in May 2019, all of the original Avengers team member's contracts expire, and actors such as Robert Downey Jr. (Iron Man), Chris Evans (Captain America), Don Cheadle (War Machine), Paul Bettany (Vision), and Chris Hemsworth (Thor), are all up for renegotiations and possible exits.

Interestingly enough, however; ​Natalie Portman may be up for a way bigger position as well, as she portrayed Thor's love interest Jane Foster for the first two Thor films. Speaking with ​Huffington Post about all of the unseen supporting character's fates at the end of Infinity War, the directing team of Joe and Anthony Russo spoke about Portman's role with sincere secrecy.

“When we say spoiler,” Anthony Russo said of the character's fate, “[we mean] potential spoiler.”

Little is known of Foster's involvement in the MCU since Thor 2, where it was mentioned the pair had broken up. Portman, being a huge name in film, was never expected to be a mainstay as Hemsworth's love interest, with Marvel Studios President Kevin Feige telling ​Comicbook.com back in 2016 there were "many reasons" she didn't return to the role, especially since "80 to 90 percent" of Ragnarok was beyond Earth.

"As far as I know, I’m done,” Portman informed The Wall Street Journal in 2016. "I mean, I don’t know if maybe one day they’ll ask for an Avengers 7 or whatever, I have no idea," she continued, commenting on the challenge of acting for Marvel films.

"When you're making those movies, you're working with so much blue screen and so much fantasy your imagination has to be so much larger," said Portman, but she's still "fascinated" by the world, stating she's "completely open to everything."

While it wouldn't make much sense for Portman to return as Hemsworth's love interest after being absent for the past two Thor appearances in Ragnarok and Infinity War, it would make sense for Portman to take up a bigger role in the MCU after some major departures.

As fans of the Marvel Universe remember, the character of Jane Foster actually takes on the mantle of Thor when the Odinson is deemed unworthy to hold the hammer. 

We'll have to wait and see what "potential spoiler" about Jane Foster the Russos were hiding when Avengers 4 premieres on May 3rd, 2019, or even beyond, as Chris Hemsworth has also expressed interest in renewing his contract for a Thor 4.