I don't think Google want to clutter up their decent sized lineup of "Nexus" devices with Chromebooks and such. Isn't that why the Nexus Q was supposedly discontinued, because the phone and tablets made it essentially obsolete?
Nexus Q was not discontinued. it was delayed for improvments.
chromebook is a netbook. Nexus 10 is a tablet. chromebook can become a full fledged desktop. but there are rumors that chromeOS will merge with Android.
like when you connect android to a dock it turns to chromeOS with Android integration