I think it's very much genuine. Most of that extra gubbins has been mooted pretty much since The Black Dossier was first announced, and usually by Alan himself, but it's been some time (a good year at least) since there was anything more officially confirmed. Last I heard, for instance, the record had been long since abandoned.
So it's great to hear from the bearded one himself that's it all still planned and imminent. Also thrilled to hear it's morphed slightly into a sort of 'source book' detailing the entire history of the League.
Safe to say I can't bloody wait.