It is like every other library, there is the pickup: the library catches the eye, solves most of the problems; people love it. Then comes the constant: the library has been the de-facto standard for quite a while, people have been creating all sorts of forks from it, hacking it and whatnot. Then comes the sad part: its decline. People no longer use it. It's good, but only for demonstration purposes. It becomes stale. Not well maintained, and then the core contributor stops developing it.
Not to hurt anyone, but Knockout.js seems to be the perfect fit here. It saw its ups and downs. But now, with the latest technology and their requirements, it's not keeping up so well.
But, let's be an optimist. And take the example of my beloved AngularJS for a second here. It saw its ups, (and downs), but then: some valiant guardians of the galaxy... that was my last Star Trek reference, I promise. The point here is that it's now being actively developed to support the latest features (TypeScript, ES6, etc.)
For jQuery, I have only seen it get more momentum; it hasn't stopped, or slowed down. And remains to be the industry standard in battle-tested, DOM manipulations.
In conclusion, after 10 years, IE may be as good as WebKit; people will start using the trailing comma... but, as far as I think, jQuery "should" (RFC 2119) be the standard. The community is huge, big companies are using it. Who knows? ;)