Regardless of the adoption rate of QUIC, TCP is going to stick around for many, many years.
I agree with this and would add that the HN crowd is very HTTP browser and API centric. There are hundreds of thousands of applications that will be using TCP and not be updated until the internet is shut off. This is especially true for B2B applications. Just getting them to update cipher protocols is like pulling teeth, each time. There are an amazing number of "business critical" applications that are running ancient libraries, protocols, etc...
TCP and UDP will never go away but browsers and some API libraries may stop using TCP. More likely additional Layer 7 protocols may get added to TCP and UDP and people will use what works best for their application needs.