[fulafel]

From WP I get the impression that the work-in-progress now called HTTP/3 was not necessarily designed supposed to supplant HTTP/2:

> On 28 October 2018 in a mailing list discussion, Mark Nottingham, Chair of the IETF HTTP and QUIC Working Groups, made the official request to rename HTTP-over-QUIC as HTTP/3 to "clearly identify it as another binding of HTTP semantics to the wire protocol ... so people understand its separation from QUIC"

Any opinions on how things are likely to play out?

[sseth]

I believe this is the separation of the transport layer protocol (QUIC) from the application layer protocol (HTTP/3). QUIC can be seen as a replacement for TCP. HTTP over QUIC then becomes HTTP/3 - with improvements in latency and head-of-line blocking over HTTP/2. So in that sense it will supplant HTTP/2 as QUIC gets adopted more widely.