As long as they don't change the spec, this will only be available to special locally installed apps in enterprise ChromeOS environments. I don't think their latest weird app format is going to make it to other browsers, so this will remain one of those weird Chrome only APIs that nobody uses.
> special locally installed apps in enterprise ChromeOS environments
There was https://developer.chrome.com/docs/apps/overview though, so this seems to be a kind of planned feature creep after deprecating former one? "Yeah our enterprise partners now totally need this, you see, no reasoning needed"