It would be kind of a fun twist, her becoming the next Thor. She's already an established character and even got the Loki stamp of approval. I'd be down for it.

I don't think they'll be getting rid of Chris Hemsworth any time soon, though. He's way too popular among movie crowds. Then again, Marvel has been known to take a lot of risks. Who knows. Depends whether or not Natalie Portman would want to do it.