So unless the Third World War hit them harder than the western countries, it would make sense for them to be represented in great numbers in Starfleet.
Heh. Hey, it's their (don't forget about India) century, afterall. Better start learning some mandarin asap ;)
And what's this WWIII thingy in Trek? I'm kinda unfamiliar with it!
iirc our history is basically already somewhat diverged from Star Trek's...Star Trek had the so-called "Eugenic wars" in the 1990s (that's where Khan and his genetically modified supermen came from). Then later, in the 21th century there was a third world war (that's supposedly when Colonel Green who is sometimes mentioned as an historical villain committed his genocidal crimes), though details have been left unclear. Earth was devastated by it and only slowly recovering when Cochran developed his warp drive in the 2060s.
Why I know all that nonsense? Well, I used to watch Star Trek. Not interested in the new series though, for me Star Trek died with Enterprise at the latest (Voyager was also already quite bad, and even TNG doesn't hold up that well when watched today imo). It should just be retired, hopefully the new series will kill off the franchise once and for all.