Hmm, I'd define that as "deprecated", not "obsolete". Many extant H2 deployments are stable and performant, and if they're eg fronted by an H3 CDN, the migration ROI might be questionable. /$.02
The h3 juice is worth the squeeze. 0rtt TLS, BBR, HPACK, etc. You can roughly achieve this with a carefully configured h2 deployment across multiple layers and packages or just move to h3 and let the app layer handle it all. We baked all of the best practices into h3, the world just needs to move on.