Inner El Guapo said:
ATYCLB was about 18 months about POP was about 15 months. HTDAAB was about 2 1/2 years.
HTDAAB was an anamoly even for U2's later and longer sessions. I think a solid year in the studio would produce an album by spring 2008, and factor in some token U2, producer, label delay bullshit and it's still Fall 2008.
Even if they finished the album late this year, they wouldn't release it until fall 2008, because they wouldn't do a spring release. As Paul McGuinness put it in U2 By U2 (and I'm paraphrasing here, because I don't feel like getting the book out): "There's no point in a band of U2's stature releasing an album during any time of the year but the last third." So if an album isn't finished by September or so, it's not likely to come out until at least a year later.
But don't forget, when we're talking about how long HTDAAB took, they really only worked on it for a little over a year. They worked with Chris Thomas from March 2003, through the summer, and "finished" in time for a Spring release, and then they worked with Steve Lillywhite for six months. Add those two figures together, and you get about a year, maybe a little longer.
So if they spend a good year working on it (not counting anything they've already done, either at Abbey Road or last summer), then they'd be finished next spring, well in time for a fall release.
But there's also still the chance that they've already got a nice handful of songs waiting to happen, and will be able to get an album done in time for a release this year.
I should also add that it's implied in U2 By U2 that the reason the songs from the HTDAAB sessions with Chris Thomas didn't feel finished enough to be released in 2003 is because he didn't know how to push them, and couldn't deal with their unusual recording style of jam, jam, jam, jam some more, keep jamming until you make something. We already know that Rick Rubin (if they stick with them, and I hope they do) is not going to let them do that, at least not in his presence. So that already implies that he's impatient enough to push them to just freaking get it done.
And these are just becoming random thoughts on the subject. I'll stop talking now.