Kate gained interest in Fractions Clinton Barton Hawkeye book when he somewhat openly turned the title into a Kate Bishop book. After that each new title that seemed to be about Clint was really about Kate. It was a bait and switch type marketing ploy but it seemed to work...Kate has her fanbase.
I'm not sure you could call her a breakout star since it was built relatively slowly but she has her place for the demographic Marvel is trying to sell to with her.