I don't think you can write off any of them. Some players, no matter how talented or how much promise they show, take longer to develop than others. Look at Schnyder. I remember back when she was being hyped as a future star, then the reports of all sorts of attitude problems, strange diets, etc. and honestly, she's played her best tennis very late in her career, after getting her head sorted out. Mauresmo was talented, but did not fulfil her potential until 2006, when she was in her mid 20's. Henin herself really only became a great player within the last few years of her career.
Right now, Wozniacki, Cibulkova, Cornet, Radwanska are having more success, but IMHO none of them have the weapons or specialness in their game to make them lasting fixtures at or near the top of the game. Vaidisova has a huge game, "ballbasher" or not, and if she gets her attitude sorted out, she will be an elite player eventually. Paszek has the groundstrokes to compete with anybody. If she ever manages to improve her serve, she will be top ten for sure. Having four different coaches in the last year can't have helped her development as a player. If she stays with one for awhile, she will improve dramatically. Mirza is probably a Top 20 player but has never shown consistency to go much beyond that. Golovin has a nice game, good forehand, good serve, and could hang around the top ten if she ever got--and stayed--healthy. But there's time yet for that. These players are all young. Some of you act like if you haven't won a major or reached #1 by 15 you're over the hill. In reality, it's only a very small number of players who ever win majors or peak as players before they are in their 20s.