The only connection that I can see between Mistborn and Inception is that Christopher Nolan would probably make an awesome MB movie.
I think the best interpretation of Inception is that the whole film, from one end to the other, is a dream. The only "real" people are Cobb and Miles (his old teacher), and possibly Ariadne and Saito. The idea that's being incepted isn't the whole plot with the heir and the corporation, it's the idea that Cobb needs to accept his role in Mal's death, and then he needs to wake up and go home to his kids. It's only at the end that he finally abandons the dream, when he lets go of Mal's totem.
Remember, that top was never
his totem, and he made it quite clear that A)a totem must never be handled by anyone else, and 2)a "tainted" totem can lie to you.
Hence, Mallory's spinning top has been lying to him the whole time, telling him he's awake when he's not. His guilt over her death has trapped him in a series of layered dreams where he can wallow in self-persecution. Miles provides him with Ariadne (named for the princess that helps lead Theseus out of the minotaur's labyrinth), who's particularly key to getting Cobb to recognize what he needs to in order to get himself out of his own personal hell.