If Khan Noonien Singh and his merry band of supermen re-emerge in the Abram's Trek (while I hope the do not) I feel they should alter his origin by swapping a zero for a one: change "tyrant from the late 20th century" to "tyrant from the late 21st".
By doing so they'll save themselves the headache of trying to explain to everyone how the hell we had a Eugenics war and at least one inter-planetary spaceship sitting around 17 years in our past without anyone remembering it.
Despite this being a "huge" departure from continuity I think hardcore Trekkers (who hated XI) can get on board this for one good reason. It establishes that no, this not the same universe as the Roddenberry Trek. In Roddenberry's universe we had interplantary spaceships and genetically enhanced supermen by the late nineteen eighties and mid-nineties. In Abram's universe we did not.
All of the departures and changes from the continuity that happen in the Alternate Reality happen not because of some fanwank about Nero's incursion changing the course of history but because its a whole new universe that bears only a striking similarity to this other one that existed before it.
The bickering about Chekov's age, the ship's size, Romulan and Klingon appearance, bridge design, costumes changes, where the Enterprise was built, how many Nacelles are needed on a ship, etc... all becomes moot*... because its a whole new universe!
*while 'moot' in fact mean debatable or open for dispute, I'm going for common usage here. As in "insignifigant, pointless, or academic."
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.