Portman is very hot right now, garnering significant Oscar buzz for her performance in the current festival favorite Black Swan (Eric Snider calls it the best of her career). And next summer she'll show up in another big comic book movie, as the love interest of Thor. However, in spite of her ability to mix it up with everything from period drama to fanboy genre fare -- and with an expected starring role in Pride and Prejudice and Zombies, a combination of these extremes -- but a solo show like Gravity will be a challenge for anyone. Portman may have one Academy Award nod under her belt, but we can all agree she's anything but consistent.
If the actress signs on, she'll appear for a bit with Robert Downey Jr. -- making up for the fact she won't appear in The Avengers, I guess -- who is attached in a supporting role as one of the station crew killed off early by an exploding satellite. As for the idea of substituting for Jolie, coincidentally Portman is also reportedly being wooed by Terrence Malick for a Jerry Lee Lewis biopic he's developing with Angelina's other half, Brad Pitt. Hopefully we'll hear more about that curious project soon.