How long has Age of Ultron been in development? Well, we had a prologue appear in April of 2011 (and a second prologue show up in September of that year). We know that Bryan Hitch finished the art for his half before he started on America’s Got Powers (which launched this April), and also that it doesn’t reflect current Amazing Spider-Man/Superior Spider-Man continuity when it launches, although it will apparently catch up at some point. But an easier way to check may be to look at this double-page spread released to CBR and see what’s out-of-date:
So, let’s see: Xavier’s alive, Hawkeye’s in his old costume, Carol Danvers is a Ms. instead of a Captain Marvel, Bucky Barnes is Captain America… But, wait: There’s more going on on that wall that just old continuity, because said wall also features characters that (a) have been dead for awhile and (b) Age of Ultron writer Brian Michael Bendis himself killed off: Sentry? Ares? There’s also a mention of Rom, weirdly enough. So is this artwork that’s been lapsed by current events in Marvel continuity, a tease that part of Age of Ultron takes place in an alternate timeline, or something else altogether? It’ll take until the start of the event next year to get an answer – but it’ll be interesting to see how much of the above spread gets corrected/altered in the coloring/lettering process before it sees print, too.