It had a better opening weekend than First Class and The Wolverine, and the first Thor and Captain America movies, if you want to make this a Fox vs Marvel Studios thing (which I know fanboys LOVE to do). Plus, if you include its worldwide gross, it's already at $278 million. Over a hundred million more than its budget, in a single week. It will perform just fine.
Not every super hero movie has to hit a BILLION to be successful.