This may actually not be a what-if question and could have a pretty solid historical answer, before the mods show up. I don't have the data and I don't have the capacity to answer it but our resident First World War mastermind /u/NMW made an offhand post a few days ago in response to me:
So while 1 million deaths for the British Empire and 1.2 million deaths for France may seem like a significant amount (because it was and is)
It does seem like a lot indeed, but it also weirdly fails to register on a national level for many countries where the census is concerned. If you look at the statistics recorded by respective censuses before, during, and after the war, there is little evidence in the hard numbers that the war even took place. For all that we speak of "a lost generation", the numbers bear out a far different picture -- a picture in which the war more or less supplanted the expected mortality of the period in terms of cause rather than in terms of actual amount.
Perhaps he could come in an enlighten us on this detail? But from what I understand, and what I've kind of gotten in broad strokes from my reading on the topic, it actually did not impact populations as significantly as we seem to believe.
Sorry, but your submission has been removed because we don't allow hypothetical questions. If possible, please feel free to rephrase the question so that it does not call for such speculation, and resubmit Otherwise, this sort of thing is better suited for /r/historicalwhatif.