Hell, the most recent winner of the Classic Tetris World Championship (which plays NES Tetris) was only 14 when he won the 2021 competition. The speedrunning community for NES games also contains a lot of people much younger then the games they're playing.
Given that, I think I can say with confidence that NES games will transcend a particular generation because they already have. And there's no sign of that slowing down anytime soon.
Granted, this is already niche content, and it will continue to be going forward. But I bet a lot of people watching those videos weren't even born when SMB came out or have even used an NES.
The N64 content is a different league though. It's not nearly as easy to understand and follow. Plus, Mario64 is written in C and most of the content I've seen has been people adding features to it (HD upgrades, ray tracing, 60fps, etc).
(And I'm still continually surprised that 80's-90's retro gaming/computing as a whole is such a popular hobby! If my teenage self had a crystal ball, he would have been very pleased to learn this.)
Super Mario Bros. isn't a garbage heap though, it's more like a statue or a mosaic.
I was thinking more like will it end up like a forgotten pop song from 1890 or something like a Tchaikovsky song that's still played and appreciated (and not reliant on nostalgia for continued attention).
I have nostalgia for Super Mario Bros., and that's why I pay attention to it. It's getting old enough where we might be able to perceive effects independent from nostalgia (though I think there may now be a phenomenon of "nostalgia for other people's nostalgia" that may still make accurate perception difficult).
But also, the NES-era games have aged better than earlier games. As much as I love River Raid, it's no Super Mario Bros. Something about on-screen menus (what do you mean I need to hit "reset" to start the game, Atari?), having more than one button, and enough processing power for decent physics.
Speedrunning seems to support this idea. That’s also one of the reasons retro games have been analyzed in such depth.
video games aren't just for young people : )