[M2Ys4U]

I don't think it's unreasonable to state that we will never deploy a new IP protocol again.

At least not one that works over the general Internet - controlled intra-organisation networks might possibly be able to do so, but very rarely.

There are too many broken machines on the Internet that assume all IP traffic is one of TCP, UDP and ICMP. And far too many are configured to screw up ICMP too.

So new protocols MUST use TCP or UDP as their base layer instead of raw IP.

So yes, QUIC uses UDP, but that should be considered an implementation detail. A hack for the lack of IP support on the Internet.

HTTP/3 uses QUIC like HTTP/1 and HTTP/2 use TCP + TLS, but QUIC is not limited to use by HTTP/3.

QUIC's development has been, basically, paused while HTTP/3 is finalised and then the IETF will pick up where it left off and work out how other higher-layer protocols will work using QUIC as the transport layer.