It's not a replacement/ enhancement of HTTP, it's definitively not a Transport layer. It has no use/gain for webservices, and as single page apps tends to optimise resources delivery (webpack, browserify, scss, stylus & co, very few resources are left to deliver) so no urgent "need" for it here.
So, for an _application layer_ it's comming a little late, i guess "block SPA" with intrisected client side & server side (nodejs/ express & spa) apps might gain of it, but it have to be considered as the very first line of the app developpement , the transition/ enhancement cost / gain ratio for existing apps is too hard to plan.
Great writing !