[danpalmer]

> for example browsers still try to establish a TCP connection first unless they know for sure the server supports QUIC

As you alluded to here, you can hint a networking implementation with QUIC supporting servers. This feels similar in practice to HSTS Preloading, most of the benefit of full HSTS comes from a small number O(100k? 1m?) of domains being pre-loaded as HSTS supporting, and that's just distributed with browsers now, a fairly straightforward solution. The same could probably be applied for QUIC.

> which I admit also take up a large chunk of the network traffic, is QUIC really replacing TCP in the general Internet?

I guess this depends on whether you're looking at aggregated traffic, or distinct traffic destinations. Neither of those is more important right! If YouTube/Netflix move to QUIC, that's a very significant amount of benefit for the internet and users. Equally if all wordpress sites on shared hosting disappeared because TCP was no longer supported, that would also be a very significant impact. I think the headline saying "QUIC is displacing TCP for speed" is very fair, but over-extrapolating from this would be going too far.