I think if they don't release it by the 10th anniversary, then it won't ever be released. After that it'll become a DVD about a band making an album 11...12...15 years ago or whatever, and I can't really see Warner doing that. The 10th anniversary might be our last shot at this ever going public.
However, I'm not a fan of the 10th anniversary deal. I think it's probably a logical choice for Green Day/Warner or whoever to make, because in 2011 the timing seems off. A documentary being released 7 years after the album, with another studio album in between just seems like an odd time. But... I'm hoping it won't be promoted too heavily as a 10th anniversary thing, and promoted more as a documentary about a great album.