I haven't looked at this as a formal model or anything, so this is mostly arbitrarily put together, but it seems to me that the current trend, stretching back to the late '90s, is that all revivals are a "classic" but forgotten superhero brought in fresh, usually as a minority and/or woman (all of the new JSA, for example, plus the new Blue Beetle, which is an exception because it's actually been a really good book). It's hard to imagine anybody getting excited about the new Crimson Avenger, for example. "It's the Crimson Avenger, but more violent, and a black woman!" Huh? But then, there's also a counter movement to "put everything back," like the current Green Lantern title and (apparent) upcoming resurrection of a certain classic Flash.
Prior to that, the current heroes were replaced in-story with fruitcakes with nothing to recommend them other then novelty (Reign of the Supermen, Knightfall, the story where Wonder Woman dies, Emerald Twilight, and so on), which is mostly the early '90s. I don't know as much about Marvel, especially at the time, but for a while, it seemed like DC was populated with hastily-constructed bumbling sidekicks who were artificially promoted by their mentors' deaths. And they were all fine with killing lots of people.
Throughout the '80s, the heroes were kept, but everything around them changed substantially, whether by retcon (DC/Crisis) or major changes that didn't last (Marvel/Secret Wars). Sometimes this was part of a big event (as mentioned), but not always (Batman, the Teen Titans, and the JLA all got non-Crisis-y "silent" revamps). Almost always, the move was to depower and make the characters more cynical.
Prior to that, I haven't really given it too much thought, but the late '60s and '70s had another explicit move to modernize and reduce fantastic elements (Ditko's Blue Beetle, O'Neil's Superman and Wonder Woman, the superspy Martian Manhunter, and so on) except in the context of the new horror comics, and while I'm not convinced that I always agree, the general consensus is that the '60s ran exclusively on space travel and gorillas, and the '50s is populated with an awful lot of atomic-powered heroes, but that seems to go further off track...which I guess makes sense, because we're getting closer to the first iterations.
Movies seem to follow their own logic, of course, a combination of what stories seem to be popular, what actors seem to be popular, and what special effects are available. Shake it too hard, and you get Catwoman...and that nonsensical Captain America movie with the Italian Red Skull.
