We know there was a golden age and a silver age. Conservative people like to keep it short and pretend there's no age after that, as if what we've read after that had no distinctive tone. Some deny the dark age and some go as far as denying even the bronze age.
I think that there are ages indeed. They often keep some aspects from the previous and go against the rest.
The way I see it, the golden and the silver ages were mostly popular versions of modernist literature, done for merely entertaining purposes and mostly for kids; while similarly, the broze and the dark ages were popular versions of postmodernist literature, done for entertaining purposes mostly for young adults, only the dark age reached high artistic values during the 80s. Each era has its tells, but it's hard (and limiting) to label each work and, even more, each author. Although they might occur more frequently in one era, particular themes, techniques and situations can appear in any of the rest, which is why I consider the narrative style and art better ways to identify eras. Modernist ages tend to place the characters in the scenes as a sitcom or play, while he postmodernists love to play with the "camera"; modernist writers kinda repeat what the art is already showing (which makes the story feel a little dull or tedious), while the postmodernist, specially the dark age counts on the reader to keep up.
My tentative answer to my own question is that we're past the dark age, and that the starting marks are JLA: Midsummer's Nightmare, Kingdom Come, Marvels and Supreme. However, their precedents are Giffen's JLI and Animal Man, in that the current era is nostalgic for the silver and golden ages, idealistic like them, but driven by shock value and keeps using po-mo elements like deconstruction, pluralism, pastiche or metafiction.