For me personally, the warning signs started with 2005's How To Dismantle An Atomic Bomb, which not only featured an unwieldly title but worse, subtle reworkings of vintage and tried but true U2 sounds for new consumption. The accompanying tour also felt like a retread of their highly successful 2001 arena tour that culminated in their blockbuster set during Super Bowl XXXVI. That 2001 U2 show at the HSBC Arena was sensational and an intense communal experience that had the whole place jumping; the show in 2005 however felt a bit hollow... even though they played lots of material off of Achtung Baby, my favorite U2 album. At the time I forgave them because it was the end of a long and stressful tour, but I felt the same ambivalence watching the obligatory live dvd, and it worried me.
Then U2 delivered No Line On The Horizon (unwieldly album title alert) in 2009 to a pretty big thud, which was the result of the band's ill considered desire to pursue Middle Eastern fusion prog rock (with a few strained sounding "hits" interspersed for fan service), but it was the title track that bummed me out the most because it was a blatant rip off of the old U2 b-side "Lady With The Spinning Head," which was itself a dry run for classic Achtung Baby album tracks "The Fly" and "Zoo Station." It was bad enough that U2 thought they could slip that by their die hard fans, who would remember the song from the infamous and widely circulated stolen tape bootlegs of the recording sessions from Berlin, the single it was originally featured on ("One," with the brilliant David Wojnarowicz cover), or 2002's The Best Of 1990-2000 & B-Sides compilation. The real rub however was the stark realization that at the end of the first decade of the 21st Century, U2 was out of ideas.
Funny and telling story: The U2 "360" show at the Rogers Centre really felt like some of that old magic was back after the No Line On The Horizon dud. The band gave it their all, and with Bono preachifying at every opportunity (never a line wasted with that guy- the result of hanging out with too many politicians), it felt right, with the communal experience restored. Of course upon further review I concluded that was in large part due to the ridiculous and brilliant stage design- you remember the vaguely Dalekesque space claw (the band even went onstage to Bowie's "Space Oddity") featured in the the accompanying video clip that actively incorporated the crowd into the band's visual/spatial tableau enjoyed by said crowd. Credit is due where credit is due, it was an inspired decision that worked artistically and commercially from a ticket selling perspective, but at the time I was all warm and fuzzy, and like many of the faithful I wanted to soak the experience up until the very end. But after a few post show songs on the PA the staff ushered us out, and no sooner had we cleared a point in the tunnel near some Portapotties, an "all clear!" was given into a walkie talkie, and a stream of big rig trucks started ripping 30 mph into the backstage area, one after another in a frankly surreal display that amazed the exiting die hards. Time is money, the space ship was due in another city, and U2's organization clearly didn't mess around.
U2's organization has a problem though, and that's the seeming fact that the band has run out of creative gas. There is a precedence for this: fellow 80's stalwarts R.E.M. soldiered on after the departure of Bill Berry in 1997 to mixed success until their inertia ground to a total halt on 2004's torpid Around The Sun. That said, by the time they were recycling their original pre Chronic Town punk sound on Accelerate, R.E.M. knew it was over, and after tidying up their affairs with the largely unremarkable Collapse Into Now in 2011, they honorably called it quits on their own terms... and proceeded to seemingly fall off the face of the Earth.
U2's organization also just went through a seismic shakeup (chronicled by Toronto DJ, music writer and U2 watcher Alan Cross) the saw the retirement of their long time manager (and unofficial/official fifth*) member Paul McGuinness, with Guy Oseary (Madonna's manager) taking over day to day U2 operations. It's easy to forget that while U2 got started as teenagers, it was grown ups who tended the flame, and now after 30 years, many of those vital parts of the U2 family have moved on, with the organization merging into another organization built around another long in the tooth pop star. Paul McGuinness was U2's chief grown up and the only manager they've ever known, and among U2 watchers, there's a real question as to how long they'll continue without him steering the U2 ship of state.
Which brings us to right now. The band snagged a Golden Globe for the nice yet unremarkable song for the recent Nelson Mandela biopic with Idris Elba. Cross linked to an uncredited ditty that's allegedly an outtake from U2's upcoming album, a ditty that sounds suspiciously like vintage U2 (I mean come on, that's clearly Dave Evans playing that classic, vintage Edge guitar), and U2 is set to unveil the first single from the Danger Mouse produced album set to land later in the spring during the Super Bowl thanks to a possibly unholy alliance with Bank Of America ("the most hated bank in America").
With the gears of the U2 machine turning again, and on the biggest platform, will it be for their last hurrah, with the big valedictory album roll out and subsequent swan song global mega tour? Will anybody beyond their legion of fans, and the fans studying the signs, even care? Hell, R.E.M. didn't give us fans a farewell tour. I hope U2 does, but I'll cross that bridge when I have to. Maybe U2 will catch their fourth wind, and emerge creatively recharged, relevant, and cool with Madonna's manager coordinating the show. I'd be cool with that; they've been the soundtrack to my life and I'm not against them keeping on keeping on so I can grow old with them like Stones fans have with Mick and Keith. If not, well, I might be OK with that too, if it's time. Might be.
* Unofficial because obviously he wasn't part of the band. Officially because they split U2's take 5 ways. Or at least they used to.

Good read. I'm interested in the new release and I'll be downloading the free song on Sunday, but I'm not getting my hopes up. There were a few good tracks on No Line, but overall I don't go back and listen to it. I was at the Toronto show, but I didn't really "feel" what you felt..it was a good show. Couldn't help thinking about seeing them in their heyday, but I was too young. Would've loved to see the ZooTV tour. I do feel they have good songs in them yet.