I mean sure? It's clear PLT and other applied CS fields are now as good as dead. You're never seeing new React or Python emerging ever again.

And unfortunately mathematics is much more fundamental to human endeavor than this.

I don't think that's true. Domain experts with the desire to create and experiment aren't going away any time soon.

Sure we are free to tinker, like the guys doing model railways. With about the same impact.

We'll have to check back in 5 or 10 years to see if anything new has been created.

It is getting a lot harder for those people to justify using OpenAI to assist such endeavours. Afterall, OpenAI might just front-run you if they hear a rumor you solved some marquee problem that they can brag about in PR campaigns.