I don't know that it's a matter of if she has what it takes. Sasuke has a way of making people want to help him no matter how badly he treats them. Take the way in which Karin escaped prison to find him even after he tried to kill her, and the manner that Taka reunited with Sasuke in their latest appearance in the manga. When the members scheme it's always for his benefit.
It might be a matter of what team she's on, so she could be perfectly capable. When Sakura does something for Naruto on her own time it backfires, like with the soldier pills. When she is being extra super kind to Naruto it's when he's suffering and she gets depressed. Being on Naruto's team might be what is making her useless. If she were on Sasuke's team she might actually become smarter. There was one case (in the Forest of Death) when Sasuke was acting like a wuss that Sakura was capable of giving him a few words that made him grow up.