Forum Discussion
Hubs and Site Collection Archtectures
this ignite https://channel9.msdn.com/Events/Ignite/Microsoft-Ignite-Orlando-2017/BRK2393sets out the approach that is now being preferred https://channel9.msdn.com/Events/Ignite/Microsoft-Ignite-Orl...
Per our other conversation, the main limitations are that you can only link to one hub and a hub cannot belong to another hub.
Virtual structure would be nice, but with this it is very flat.