She's still a major act, she's just not turning out to be the artist everyone expected her to be 3-5 years ago. People were expecting an artist on Michael Jackson, Elvis, The Beatles and Madonna's level.
Just because she's not living up to that doesn't mean she's failing. It just means she had a huge, revolutionary debut, but hasn't been able to sustain the numbers she saw in her debut. It was an insanely huge debut btw. Just because she's not living up to who we all thought she'd be, doesn't automatically make her a flop. There's more competition in 2014 than there was in the 80s and 90s. The fact that she dominated in 2009-10 is an achievement in its own. More than any of us will ever amount to
Not like that's hard but still.