If the current trend of new hardware for old consoles is any indication, I think modern gamers don't have much to fear. If there's an audience that wishes to play these "future retro" systems, there will be people that will make the hardware to work with it. Adapters that lets your Xbox 1080 controllers work with your Series X or a wireless controller dongle to make your Nintendo ShroomStation's Tactile Squish Ball controller work with your Switch. And if not adapters, new pieces to make your old pieces work like new.

I think the biggest concern will be when some games that require some sort of server to connect with and phone home/update/etc. Will the e-titles be preserved or will they just disappear into the ether like they never existed? Or what about games like Animal Crossing: New Horizons where the cartridge was bare bones and the rest of the content was downloaded later? The hardware will probably still work, but you won't be able to play a lot of games without their day one fixes or content. Ouya was lucky that its servers were preserved and are now running thanks to enthusiasts, but they weren't a company as tight fisted as the likes of Nintendo, Sony or Microsoft.