imho, I think your being a tad pessimistic. Back in January at Innings Festival, Billie Joe said we'll be back next year. Rob Cavallo confirmed this by saying the new album will be released early next year. That's early not late as you suggest. We already know on here that the album is finished. So, for me that's Jan/Feb for new album and start of US/World tour. I'm drooling already.
As for anniversary celebration, Dookie 30th & AI 20th. Well in the past it's only been for 25th, for Dookie, Insomniac & Nimrod in various forms to celebrate. Although, having said that, back on April 19th they celebrated the 33rd anniversary of 39/Smooth by issuing the never seen before video of a live performance 'Paper Lantern' in an Oakland backyard just before the album release, March 25, 1990. Released on IG. Awesome.
What would be really really special to celebrate next year, especially for the fans, is a 'Bullet In A Bible 2'. Say next fall/autumn. A CD/DVD, of a full live show of the new album. Uncut this time, from start to finish. Especially for the fans that can't get to see them live for whatever reason. Maybe for that show, to include some Dookie/AI classics. That would be really cool. Dreamland, I know. But if you dream and wish long and hard enough, they sometimes come true.