The issue I have is that there are as many CHARACTERS of WW2-or-1 vintage around, not humans. My beef is not about the realms of physical possibility, or their respective humanity or inhumanity - this is comics; I've long since learned to ignore such stuff. Also note that I have included no immortals on the list - existing for thousands of years is much more happily general; it doesn't tie them down to any one time. My beef is that there are so many characters from roughly the same time period - it's like they're all members of the same club, y'know? They're members of the World War Club, and you bet your sweet bippy that, at some point, EVERY SINGLE ONE of its members has encountered every OTHER single one of its members. And we are now in the 21st Century - as time goes on, their continued existence in the present will become more and more implausible. Captain America's period of hibernation has already been extended by some fifty-odd years (a recent retcon has him adjusting to modern-day television after being revived and being horrified by 'Fear Factor'), and he at least has the 'frozen in ice' thing as an excuse - most don't even have that. As WW2 recedes further and further into the past, the continued presence of so many characters who've participated in it is going to start seeming somewhat quaint, to say the least.