Unless they lose 99% of their users, there's enough demand. Your level of pessimism on this specific detail is ridiculous. Tor might not last forever, but it won't be lack of HTTP support that kills it.
If you wait a few years for HTTP/3 to settle, proxies will be available that could be glued into tor inside a weekend hackathon.
If you wait a few years for HTTP/3 to settle, proxies will be available that could be glued into tor inside a weekend hackathon.