I'd argue that there's a resurgence in non-JS web sites due to server-side rendering. React and Ember both support this really well at this point. So, you'll actually get a non-JS view of your SPA then progressively enhance this with JS.
I'm not using fastboot (just not worth going from rails to node in our use case) but if you have set that up, won't all of your users see a non-js website before they see your js website?