I really hope this actually means "full" Chrome (as in, plugins, chrome apps, all the rest) and "full" windowing capabilities are coming to Android and not just that Google is cancelling ChromeOS and using some renaming and tweaks to Chrome on Android as a fig leaf to pretend otherwise.
I imagine that the lack of a DevTools front-end and extensions on mobile are product decisions, not technical ones. There's probably a compiler flag you could flip to compile an APK with support for both. Mobile devices have historically been small and underpowered; Google may have decided that including extensions would expose too much surface area to slow the browser down and/or kill the battery on a mobile processor. Similarly, they must have decided that the DevTools UI was designed for computers and wouldn't make sense on a small touch screen.
I'll be very surprised if they remove either feature from future Chromebooks.
