Well, that all sounds like lovely fan fiction that I do not follow for anything. Since WW3 is considered a major event, with figures like Singh, Colonel Green, etc. being challenges to overcome, as well as the efforts to unite Earth and become better, I think that TOS would loose something of its coherence by removing WW3.
Honestly, I think that we can live without WW3. To dystopian for a great series like Star Trek with its hope for a better world in the future.
But there should be some way to keep Khan and don't ruin the established Trek history too much.
I'm Star Trek's Fix-Master, you know.
When something isn't right and can be fixed, I fix it.
So far I have:
1. Restored Kes and eliminated the damage done to the character in the episodes
The Gift and that horribole episode in season 6.
2. Done away with the "nine-year lifespan" stupidity for the same character.
3. Found a perfect solution to explain the problems with shuttles and torpedoes in Voyager by coming up with
The Shuttle and Torpedo Building Team.
4. Found a way to bring Neelix to the Alpha Quadrant.
5. Restored Gowron by stating that the "Gowron" who was killed by Worf was a cardassian agent who had had his appearance altered to create conflict in the alliance against The Dominion.
6. Came up with a lot of solutions for certain problems in the Trek series, like in
Threshold, The Kazon-Ogla water problem, the Ocampa one-child problem, the Tom Paris-Nick Locarno problem, Two Admiral Paris and so much more. Most of this can be found at The Kes Website and there will be more to come.
Just go to The Kes Website and click the link: Voyager Mysteries-and how to solve them.
Personally I think that my efforts in those cases are more positive and constructive than what certain Trek producers and authors have done in recent years by blowing up planets, killed off and destroyed good characters.