Although she's played Jane Foster in Thor and Thor: The Dark World, Natalie Portman has never seemed like a stable part of the MCU. In fact, they seem to be coming up with reasons for her character's apparent disappearance at every opportunity, such as in Avengers: Age of Ultron when it's revealed she is up for the Nobel Prize. And rather than continuing to hold on to an A-list star like Portman and not utilize her, it appears she is done in the world of superheroes.
Speaking with the Wall Street Journal, Portman confirmed that she won't be in Thor: Ragnarok, which is filming right now, and that it's unlikely we'll see her in any Marvel movies.
“As far as I know, I’m done. I don’t know if, maybe, one day they’ll ask for an Avengers 7 or whatever. I have no idea! But as far as I know I’m done.”
Portman has no hard feelings over the situation, calling her Marvel experience "great". That said, it's not really a big deal that she's gone, and likely Jane Foster won't even be brought up in Thor: Ragnarok since it takes place off-planet. Who knows? Maybe she'll get a shout out from the Thunder God after all? We'll find out when Thor: Ragnarok opens November 3rd 2017.