We will get there, but probably not for the upcoming release, hoping for some time in first quarter of 2017, no promises.
In the meantime there are browser plugins that will shift any site from light to dark as needed.
Some things I’m still not seeing answered in the basic spec:
Do we want to support custom templates in the v1 of themes? I certainly think it makes sense to bundle that in there. For example, if you style your theme around a custom desktop_category_page_style that you’ve added, the template and theme are basically codependent.
Well, this is already supported in site customizations, no reason not to support it in themes.
First iteration of native themes is now merged per this giant commit.
Following up with specific #howto topics to explain the new system