Grant Morrison's annotations of Multiversity: The Just. In this article, Grant Morrison comments that:
I wanted to do something with the new generation of DC heroes that was created in the 1990s, at a time of innovation and experimentation. These younger takes on old favourites should have replaced the previous generation, as the superheroes of the Silver Age replaced their Golden Age counterparts, but a growing Silver Age nostalgia and a desire to reinstate old ‘classic’ favourites for an aging audience proved too compelling. This left many of the ‘90s new generation of characters without a direction and I wanted to explore that feeling – the grown-up Teen Titans inherited a future with no room for them!
It's an interesting idea; but I think that Morrison overreached here. First, we already had an Earth where the 90s heroes had been sidelined: Earth-0. Writing about an entire other world where the whole point was that they had been sidelined is redundant. Second, despite what Morrison later says about the likes of the Kardashians, no one wants to read a book about people who lead meaningless lives. We're seeing that particular issue recapitulate in the present, where one of the biggest complaints about today's comics being that they're too much like soap operas and that nothing that happens really matters.
What Morrison gave us works well as a one-shot commentary on a lost generation of heroes; but it doesn't work as the basis for an ongoing series. It had all of the heroes that I wanted to see given another shot to prove themselves worthy, and put them on an Earth where they wouldn't have to compete with the resurgent Silver Age heroes for prominence; but then it yanked the rug out from under them by saying that every problem that mattered had already been solved by their predecessors, leaving them with nothing meaningful to do.
Ironically, the pre-Flashpoint Earth-16 (which was based on the Young Justice animated series in the same way that Earth-12 was based on the DC Animated Universe) came a bit closer to what I would have wanted: a world with real stakes and which focused on the successors to the Silver Age heroes. In the wake of Death Metal, several of the worlds of Multiversity got reformatted with new iterations (such as Earth 2 becoming more like its pre-Flashpoint counterpart, and Earth 3 getting a fresh reboot); and I wouldn't mind seeing Earth 16 likewise getting a reformatting.
My ideal Earth 16 would be to take the DCU as it existed in the late 90s, and then project it forward under the assumption that the wave of returning Silver Age heroes and ideas never happened; and in fact that the replacement of Silver Age heroes with 90s-esque legacies accelerated. On this Earth, Oliver Queen never came back from the dead, and Connor Hawke is still Green Arrow. Graduation Day never came for the Titans and Young Justice; both are still around, although the ranks of the Titans have been somewhat decimated as the likes of Nightwing, Donna Troy, and Tempest have left the Titans to replace their mentors in the JLA. And so on. Even keep elements of the 00s that fit the theme of evolving past the Silver Age, such as the Jason Rusch Firestorm, the Shadowpact, the Secret Six, Wally's twins, etc. — although tweaks would need to be made to excise the likes of Infinite Crisis from the setting.
But I fear that DC is implicitly assuming that The Just still describes Earth 16.