I would be willing to bet that the odds of mistborn being a movie will be greater if the last 2 WoT books hit #1 on the NYT(almost a given) and his new Way of Kings book does well.
Maybe Brandon will get lucky. Some hollywood producer is a big WoT fan and they go who is this Sanderson guy? Then they read mistborn, come here and then track downt he guys who optioned his book.
I am not really sure how well Mistborn will tranlsate into a movie. A TV series might be more appropriate, but the only 2 networks that can do this well are HBO and Showtime. Free TV does not do sci-fi like this well at all. There has to be an arc in each episode which does not really translate well.
HBO is doing GRRM. I don't know if they want 2 fantasy series. There big thing is being the historical show network (I like that about them.. the pacific is very good)
Showtime does not do sci-fi anymore. They had a terrific time travel series several years ago that they cancelled mid-season (I cant remember tbename of it)