There's a little more indication of one of the twins showing up later in X-Men in a recent article on Newsarama. The excerpt is below:
[Beyond that, Carey said that "The line up of the "Adjectiveless" team is going to remain fluid for a while, with at least one very major character getting the push in a significant and irrevocable way. Characters like Northstar and Aurora will almost certainly reappear, and may find a place in the team...]
so maybe we'll see more of them after all...