The thing is just that neither Ms. Marvel or the X-Men really need each other and the X-Men have plenty of teen characters in general that they don't need Ms. Marvel.
And her more direct association/connection is with Avengers characters (even if she's admitted to fangirling and writing fanfics about X-Men). She leads a team made of mostly Avengers legacies.
At best I can see her being like Firestar.