from what I've read on facebook, so this could well be totally wrong, a memo was e-mailed out to all BBC staff instead of the correct few staff it needed to go to, advising them that they would have a new Doctor for the start of season 8, next year. Apparently within an hour of this being revealed, the BBC released an announcement that there would be an embargoed announcement by midnight that night, which some newspapers seemed to break early by revealing their Sunday front covers around 10pm onwards. One can only speculate that Matt returning for season 8 was a smokescreen to cover the upcoming regeneration this Christmas, or maybe he did change his mind, until someone high up in the BBC goes on the record in an interview and explains everything I think it'll remain one of those gray areas