Even if the browsers support modules, you still will want to generate a bundle, because loading modules on the fly would require lots of tertiary HTTP requests.
I just don't see what the point in having support for additional js language features natively is if you're forced to use a tranpiler regardless.
If you supported only, say, 50% of ES2016, and modules you could plausibly deliver unbundled native ES6; it'd be pretty cool; but modules aren't just a random feature from the pot; there is literally no serious modern web application that doesn't use them.
So... I'm struggling to see the ES2016 feature complete map (without modules) as really meaningful for anyone, practically.
https://hpbn.co/http2/#request-and-response-multiplexing
HTTP2 takes care of loading files via multiplexing, and ES6 modules take care of loading JS in proper order, no need to bundle AFAIU.
You can read more about why we'll always need a bundling step at the following links:
http://engineering.khanacademy.org/posts/js-packaging-http2....
https://medium.com/@asyncmax/the-right-way-to-bundle-your-as...
https://medium.com/webpack/webpack-http-2-7083ec3f3ce6#.74q6...