TCP is fine and isn't going anywhere. QUIC is an overengineered contraption that only exists to serve more ads. SSH doesn't need it. Postgres doesn't need it. Nobody needs QUIC except Google.
SSH's "master" mode connection sharing would benefit from QUIC / HTTP/3 head of line blocking elimination just as much as browsers would. Run a heavy rsync using connection sharing with an interactive session and you'll notice the interactive sessions latency suffering noticably.
Long-lived SSH connections would benefit from QUIC / HTTP/3 session survivability.