But she's not a one hit wonder.
Her first album did quite well. Her second album was one of the biggest hits of last year. She's had multiple number ones. She's the first person since the Beatles to have X singles in the top 10 at one time, or X singles plus an album at one and two or something. (Some impressive sounding record with regards to multiple songs/albums.)
Maybe she won't last, but she's not a one hit wonder. Her two albums have significant differences. She writes her songs partially herself. She decides on her imaging etc. Basically, she's not manufactured, which is what a lot of people think of with modern one-hit wonders (or other pejorative associated with "manufactured.")