We may have to wait for any further announcements; too early for speculation till we get an official statement.
Update (STOP PRESS): That's odd. Someone went to inquire HMV and they said that the December issue will have Nanoha on it. What?
http://yaraon.blog109.fc2.com/blog-entry-5107.html#more
They're now trying to examine the picture, to see if it's genuine or someone went to insane lengths to reproduce a genuine-looking cover of NT.