Already happened. That's why all the ads for ukie mailorder brides all over the internet...
Ukrainian brides have been a thing for over 30 years. The phenomenon antedates the internet. I first saw the ads (as I recall) on the back pages of SF Bay Guardian, the SF lefty free paper.
When Zelensky runs out of Ukrs, he will just use Poles! Then Americans, he can fight forever. Lose a tank, make a call, and get six brand new ones overnight. As long as the pipeline to Washington and the EU is open he can fight till the cows come home. The question is—how long do Americans wish to fight?