[Periodic]

You're back to the case of having one static page and then having your javascript enhance things as you go. You'll be stuck replacing elements with your JS. I still think it's a great way to think about how we render on things like mobile. Ever get those slow-loading pages where the elements jump all over the place? Or half-way through reading an article the pop-up add finally renders? We need to build those into the baseline.

Fortunately, we can reliably depend on javascript now. What we cannot rely on is internet/processing speed.

I've always found progressive enhancement to work best as an additive process. You want to define the functionality of your page and then add enhancements and verify that the base functionality still holds. If you start from the most complex behavior it is a lot harder to reason about how removing functionality might hurt the page.