Re: AD for the home user?
Can't say for W10/Home (I have the Pro-Version running) and joining AD domans. But if MS builds another WHS - why not use a "hidden" AD domain (With a nice, simplified UI) for this? No need for exposing all the capabilities to the end user nor is telling them needed. If MS does a "bundle" (Let's call it Surface/Homeserver) they can add some NFC/BT/Whatever based hardware for "auto registration" of new network devices and a simple UI from the store to enter the data on the device.
Hiding complex stuff is the idea of most developments in the Win10 UI. May not be useful in more complex stuff like a company network. But to network 2-3 tablet pc and 3-5 mobiles it would be "good enough".