Over at The Weekly Crisis, I have pieced together some hints about the upcoming return of these three characters. They have been missing for quite some time, lost in editorial limbo, where no one knew what to do with them. Should have made a Starjammers mini series or something out of it, but the hints seem to point that the characters will return to Earth. Go read the whole article.
While not concrete evidence in of itself, paired with the other clue dropped by Mike Carey, we can start painting a clearer picture of the status of Havok, Polaris, and Marvel Girl. Between these two unrelated pieces, I think you can start forming the puzzle of the trio’s comeback. It took a while, but it looks like they will finally make a (glorious?) comeback to the X-books.
I like writing these kind of articles, hunting through different sources for news that slip under people's radar. It's the closest thing to comic journalism that one can do for free, I think.