I'm optimistic that we'll see pretty widespread support, maybe 3 of the 4 major engines, by the end of 2016, with the 4th following shortly. The face-to-face meetings have gone extremely well, and all browsers are pretty motivated to ship quickly.
The Web Component polyfills and Polymer will also be updated to support the new versions of the standards.
The Web Component polyfills and Polymer will also be updated to support the new versions of the standards.