This is my preferred use of js, providing additional functionality and usability improvements on top of things that already work perfectly well with js disabled.
Users with js still get the "fuller" experience, but users who choose to disable js still have full access to the site.
But you have to implement this "extra functionality" already. Or, how are you dealing with situations where your JavaScript fails to reach your user's browser? How are you dealing with situations where the JavaScript arrives in the browser but doesn't execute?
This "extra functionality" is the same "extra functionality" as having a safety cage designed and implemented in a car. Sure, it's just extra functionality that most people will never ever use. Hopefully. Touch wood.
If it doesn't work without JS, is it going to work in a screen reader? Should developers have to implement extra functionality for the < 1% of people who are blind?
Nobody is forcing developers to give a damn about accessibility, but it's a bit sad that so many have thrown graceful degradation out the window.
The way I understand it (and I don't claim to be an expert): yes, it will work. Modern screen readers let the browser handle the JS and related parts, and it reads the displayed text.
Users with js still get the "fuller" experience, but users who choose to disable js still have full access to the site.