Let's examine the evidence...
Motive: clearly very high, they're very enthusiastic about the new songs, so much so, they've played them in public, twice. They are clearly in GD mode, any talk of side projects appears largely irrelevant at the moment. High energy, tonnes of fun. All good.
Means: they have enough new songs for an album, BJ has been writing consistently all year and at least a little during the tour, the process appears to be songs flowing out of him, rather than them being dragged out in a desperate search for inspiration. All good news.
Opportunity: unfortunately, we know nothing about what has or has not been recorded, making the timeline difficult to gauge. I agree with the notion that if they were a decent way into the recording that we would have heard talk of producers (please, Rob) or industry related articles. Also, must note that we have previously heard the recording process beginning to end can take upwards of a year.
Bottom line: 2012 would be great. 2013 - still a possibility.
Wildcard: Green Day always manage to surprise me!