I see the author's vision, but I have to say that I still favor progressive enhancement over this. Using javascript only assumes a lot about the user even in this modern age of web development.
Also as a nitpick, I would say don't make your data objects SINGLETONS, make them SINGLE INSTANCE.
EDIT: someone deleted their comment but brought up a good point that you can have progressive enhancement with this. Yes, however the author made it clear he favors the JS or nothing approach. And there's even this snippet:
>An offline first approach would be to move the entire MVC stack into client side code (aka our app) and to turn our server side component into a data only JSON API.
Here's your user assumption: 99.8% of browsers have Javascript turned on. Creating a fallback version of your app that works without Javascript is basically like developing for IE 5 -- you are completely wasting your time.
Here's another one: mobile browsers make up a majority of web traffic now, and Chrome and Safari are pretty well split in terms of share. Sending HTML tags over the wire is a waste of your users time. The idea of "progressive enhancement" should be thought of more as, "what can we display quickly on our user's screen while we're downloading and parsing the Javascript to make the application work". Note that this doesn't mean loading screens, just an initial state which shows the user progress in building up the app from that initial http connection. Regardless of the negativity around AMP, Google has made us think about what exactly we need to do in order to provide a good experience quickly and a feature-rich experience within a couple of seconds.
Progressive Enhancement was laid out clearly actually so that basic content should be accessible to all web browsers
and basic functionality should be accessible to all web browsers.
As for google, they also recommend using progressive enhancement and they even removed their ajax SE scheme posting about this wherein they even give a recommended trick for compatibility testing.
Also as a nitpick, I would say don't make your data objects SINGLETONS, make them SINGLE INSTANCE.
EDIT: someone deleted their comment but brought up a good point that you can have progressive enhancement with this. Yes, however the author made it clear he favors the JS or nothing approach. And there's even this snippet:
>An offline first approach would be to move the entire MVC stack into client side code (aka our app) and to turn our server side component into a data only JSON API.