[joahua]

I dunno - obviously different projects diverge on required backwards compatibility (Python 2/3?), but SSH isn't called Telnet v2.

For something as fundamental as HTTP the author argues changes need to be radical to drive adoption, but at the same time there's not necessarily wide-spread impetus to do so if the burden is too high. This is engineering on a 15 year time-scale, which I feel a little young (at 24) to well comprehend!

It's not just apps in the web-app sense, but user agents (all the way down to embedded systems) that would need changing to take advantage of the 'sufficient benefits'. That's a pretty massive undertaking.

[dangrossman]

HTTP 1.x will not disappear just because 2.x is available. Millions of people still run wifi networks on 802.11b; all those routers still keep on workin' even though 802.11a/g/n had 'sufficient benefits' that we build those into new hardware. There was no massive undertaking to replace all the routers in the world.

Nobody would have to change their old apps or hardware. Like SPDY, the availability of a new protocol supported by web browsers just means new stuff can optionally do things old stuff can't.