Sally thinks she ........ a medal after seeing some of the competition.
(wins - will win - win - is going to win)
Hello, Sedo: The most natural choice there (though not the only grammatically possible choice) is "is going to win." How do I know that? Because I'm a native speaker and know that's what would likely be said.
But that's not the answer you want to hear. We can analyze "be going to" here as expressing both present intention concerning the future and evidence-based prediction about the future ("after seeing some of the competition").