The Avengers: Infinity War tie-in novel Avengers: Infinity War: The Cosmic Quest - Volume Two: Aftermath is now out, and it may be the first official look Marvel fans get at what the Marvel Cinematic Universe has become after "The Snap."
There are quite a few choice details included in the novel, but the one that might interest Marvel fans a great deal, is the revelation that yet another major MCU character may now be confirmed to be a survivor of The Snap.
...That person is none other than Thor's old flame, Jane Foster!
The novel chronicles how Thor supporting characters Dr. Erik Selvig and Darcy Lewis are seeking to explain the cause of "The Snap" in Avengers: Infinity War and even how to reverse it. That quest leads them to some other gifted scientific minds pitching in, which include Jane Foster.
So is this an indication that Natalie Portman isn't yet done in the MCU and could make an appearance in Avengers 4? It's certainly a possibility - just not one that fans should hold their collective breath for. Natalie Portman has been pretty genuine in her repeated assertions that she's moved on from the MCU since Thor: The Dark World in 2013, and the MCU has progressed to make that a reality, giving Thor not one, but two other potential love interests in Sif (Jaimie Alexander) and Valkyrie (Tessa Thompson). There's no reason to pull Jane back onscreen at this point, when you can simply use her in spinoffs like this tie-in novel.
On the other hand, Avengers 4 is supposed to be a sort of full-circle closer of the MCU as we've known it since Phase I, and that could include all sorts of surprise cameos that fans never expected - including Jane Foster. She would also be a particularly relevant character to bring back as she was once connected to the Reality Stone, which could be a major key in helping Selvig potentially master theories revealed to him by the Mind Stone during The Avengers.
We'll have to wait and see what happens (in general) when some of the first official Avengers 4 promos start rolling out.
Avengers: Infinity War and Ant-Man and the Wasp are now available as a digital download as well as on Blu-ray and DVD. Upcoming Marvel Cinematic Universe movies include Captain Marvel on March 8, 2019, Avengers 4 on May 3, 2019, and Spider-Man: Far From Home on July 5, 2019.