I'm not convinced. I mean, firstly, the people who are nostalgic for this era of cinema aren't just going to die and take their consumer-clout with them in the next year. And, though we weren't in the cinema for Top Gun, a lot of us older millenials have the same attachment to these movies that Gen X does.
But more importantly, young people are predictably rebelious. When I was a child I was mercilessly mocked for having a centre-parting hair cut; side-partings were the thing to have. Now zoomers are mocking side-partings with the same fervour while rocking a centre parting.
We can all feel the Marvel backlash coming, whether we're part of it or not. I don't know whether Top Gun is an echo of the past or a sign of things to come, but I very much doubt that the cinematic superhero world you outlined is going to be here for much longer.