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.