There is some discussion about the rationale for this in another thread. I started posting technical stuff there and realized that posting here would be more useful.
Outside of the why, which belongs in that thread, I want to talk about the how.
I see that Samba is in the repository, so I wanted to give it a shot.
The packages I am installing thus far are:
krb5-config, libkrb5-3, ntp, ntpdate, samba and winbind
There's 58 other packages that go with it, but doing sudo apt-get install and these six will get you started.
Today, I discovered that using an emulated Pi has some disadvantages. Namely, without a TAP connection, the virtual pi is not able to communicate correctly with the NTP server or the domain controller.
Outside of that, kerebos5 compiles just fine and I can configure it. Samba and Winbind also compile. For the curious, I discovered that Samba4 fails during configuration, but not during compiling. Because Samba4 doesn't configure correctly, winbind4 doesn't properly install.
Again, I think Samba4 didn't configure because of the communication issues.
More work to come next week. Next week, there will be more technical details and links to screenshots.