I think it’s also important to note that not a lot of people at the time saw it as fighting Fascism, necessarily. They saw it as fighting for America and “the free world”. I say this because 1) America was doing some pretty fascist things, especially to the Japanese at the time. 2) I’ve seen several examples of “public service announcements” where they remind people that fascist views (without calling it fascism) are un-American.
So IMO, it isn’t that WWII vets are dying off, it’s that there has ALWAYS been a set of people who gravitate towards the message of finding and demonizing an other and wanting a system where the “good guys” have enough power to do what needs to be done. And with Trump in office, they finally have someone who won’t condemn their actions and even condones some of them.