Is there anything out there that is the opposite of this? Like a directory of old things that are, against all odds, still alive

Jabber / XMPP is still around and is pretty good for self-hosting a messenger.

Email, now with multiple validations and verifications.

Gopher protocol has a niche community (probably overlapping with newer Gemini).

Doom, still played and modded, and now a semi-meme benchmark for low-spec hardware.

Countless *nix tools that originated decades ago and evolved.

Like https://gamecopyworld.com :>

ytmnd, hackernews. Regarding software, perhaps vlc?