To okapi:

As Michael has already said, it hasn't been decided yet the exact way of grouping and organizing objects so maybe there will not be a clear layering system.
AutoCAD has only layers, Revit has no layers, just categories,names and groups, Max has layers, names, groups, named sets... so you can understand that there is not only one way. Layers is the classic way, but I am not sure it is the best too.
Be patient...
Creating a layer system is much work to do for Michael so at least it has to be the final decision.
I am not sure that layers are the best solution for MoI. Maybe this should be a new poll for Moi users...