Who remembers xserve?
I think Apple should come out with an M1 Enterprise chip and a line of data center/server hardware to compete with Oxide. As for an OS, why not hire Hector Martin and adopt a particular flavor of Linux (maybe partner with Red Hat)?
A product that could even compete with half of what AD offers and could manage OSX devices would be pretty incredible.
But anyway, AD will become much less relevant in the future as everything moves to the cloud, a la Azure AD.