Tbh I feel she managed to have a great career all things considered, as for continued success I guess it was the time between the eras that made people look to other pop girls coming up, also just before bionic era she made that comment about gaga (that may have been or not with ill intent) just around the time gaga became huge and perez hilton that was popular back then really went in on her and the media did as well and damaged her image. Also her persona back then wasnt the best, she was notorious for having a bad attitute and being rude to people that didnt help either, and bionic was experimental and solid but wasnt as catchy enough to keep the interest of the general people