Personally I don't see any of that happening - client-side app development on the web is a chaotic mess with no "official" (whatever that means) way of doing things. Throw into that mix the constant reinvention thats going on (yeah can't wait to see everything get re-invented AGAIN when web-assembly comes along), for what constitute incredibly marginal gains in the UI space (the web UI was already way fast enough 5 years ago without introducing mind-bending paradigms like react).
On top of all that, the very concept of web apps (in my opinion) is fundamentally flawed in that they break the web (fundamentally flawed in a similar way that Flash as a interactive platform was flawed e.g user interaction along a timeline is an inherent conflict).
So personally I expect all the client-side web app stuff to collapse under its own weight at some point. As a example, I've been a web developer for 20 years, and for my own projects at home I don't even bother with web front ends; I use QML and QT and bang out a great UI in a fraction of the time it takes to produce a web UI. It's not worth the hassle anymore, but then I have the luxury of my own projects not having many (any?) users beside myself.
As for back-end, I've actually seen a shift more towards "systems" e.g a set of isolated sub-systems interacting via event busses or queues over HTTP/JSON either as micro-services or something close to that. Then a separate "web front-end" app pull data for output/display, almost as a client to that system. So a cleaner separation of The Real System from Web Application Back-end. And in this space, things seem to becoming much more standardised means of communication between parts, whilst at the same time there is a Cambrian explosion of new tools, languages etc which can be exploited. There is very much an idea that separate sub-systems can be written in languages which can best take advantage of for the problem space.
It's very interesting to see the differences in the way the front-end and back-end communities are approaching progress/innovation.
Anyway, thats my opinion/view of it all. Sorry for the wall of text