That's why I think for businesses who want to go open source, the best model is the Chrome/Chromium model. Keep Chromium as open as you want, but keep Chrome - that is built on it - only for yourself, and only you can control and modify it. If only Android worked the same way...

I believe all Chromebooks even get all the updates from Google, though it remains to be seen if that can be maintained with more than a few devices.