I've been advocating abandoning the foolishness of irrevocably dating the Eugenics War in the 1990s for a while. It didn't even make sense in the late 1960s. For Khan to have been a ruler of a quarter of Earth in 1992 or whatever it was, "Space Seed" was asking us to believe that there was a massive genetic engineering or selective breeding program being undertaken somewhere in the East even as the episode premiered.
I don't really want to see Khan or the Augments in Star Trek 12, but if I did, I would be pleased to see them from at the earliest the 2050s.
According to the prequel novels by Greg Cox, the creation of the Augments was a secret project that nobody else in the world knew about, not even the CIA, KGB, MI6, Mossad, or any other intelligence agency-the only one that did was Gary Seven and the Aegis, who tried to stop it as best as they could, but to no avail, since Seven
spared the lives of the various kids created by the project, all of whom grew up to start the Eugenics War. BTW, this project was an international undertaking, not just something 'from the East'.