Yeah, Devon Sawa was supposed to be the next "big thing" after the Final Destination films, but nothing came of it.
I also agree with Nicole Scherzinger. I remember when she was on "Popstars" on The WB, and that was damn near 15 years ago. Her move to The Pussycat Dolls was an obviously calculating way to propel her to a solo career that never happened. Bad song choices, coming off like a bitch on wheels on The X Factor, no career direction in spite of [allegedly] sleeping with Jimmy Iovine, and age (mid-30's, so she's 'old' by pop music standards)are all factors that hinder her. She's too ethnic-looking for red-state flyover people to go full pop music and too exotic looking to win over female R&B fans who'd rather just listen to Beyonce instead.
Jessica Simpson simply doesn't have the stage presence and charisma that Britney Spears had in her prime nor does she have Xtina's vocal prowess. If it wasn't for that Newlyweds show, Jessica would still be known as the dumb bitch who flubbed her Mickey Mouse Club audition back in the 1990's.
Arguably, Kylie Minogue fits this, at least in North America. She can hold her own in Europe and Australia, but in spite of her early 2000's and late 80's pushes, she hasn't been able to replicate her success as much on American/Canadian airwaves.
Tucker Max - I liked his book "I Hope They Serve Beer In Hell" a lot more than I should. But his stories of fratboy douchebaggery wore thin (he's in his late 30's now, well past his prime for such foolishness) and the movie based on his book flopped in the box office.
Jessica Alba was supposed to be the heir-apparent to Jennifer Lopez as the next Latina It-girl, but she lacked J-Lo's charisma and ambition. Say what you want about J-Lo, but she definitely had that "It" factor and she milked it for all it's worth. Sophia Vegara has the career that Jessica Alba was supposed to have.
James Franco has had some success, but he comes off like a douchebag and a stoner and Joseph Gordon Levitt has his career at the moment.
Paul Walker had some hype and press, but he comes off wooden and boring. Bradley Cooper has his career now.