Britney tends to always have short, front-loaded eras. The first single is always huge and the follow up is usually just as big, but she really starts fading after that. I don't know what it is. It's an unusual situation with Britney. Femme Fatale is full of single-worthy songs. It was only a matter of making more of the right choices. Anyway, I still think she has done incredibly well for herself. She's been around for 13 years. Her original fans are much older now. Considering that, she is still successful. She just has to come back every few years and she can keep going.