In an enterprise there are so many applications attached to AD DS - However enthusiastic we get, I am not clear how AADJ will replace all of them. Untill once subscribe to full Microsoft vision, I am not sure traditional organization can do away with AD completely.
PKI being the primary and I guess that can be solved with Intune certificate connector. Voice (PBX) System with softphone which identifies based on AD identity. Video conf equipment in the office are again tied to AD. I am sure if we rip and replace and get every conceivable product directly tracking to Azure AD, may be possible.
Most importantly support: With personal experience the folks who write such fantastic and thorough articles are not in the field. What we get in the field are Fastrack team, which are so green - it is a joke. Their entire purpose is to push bing searched links. The folks interacting with us could not properly explain what's written in this article, short of assisting with deployment. Microsoft tech support esp. with Azure AD is.. let's not even waste energy.
So overall, though AADJ makes sense, we consider atleast 3~4 year journey before it could culminate in fully getting away from AD DS.