I mean, it IS hard to tell if Call Me Maybe will reach the success of Britney's song, but it's already #1 in six countries, and is #2 on iTunes in MANY other countries, so it's about to reach #1 in the others too.
I think a lot of you don't want to believe the success of this song. It's not just #1 for one silly week, but 3-4 weeks. Not exactly a flop.