Currently t is only possible to use cascading attributes when you have two enumerations.
In our environment we have location specific values for an attribute that must be handled in one big enumeration list and the values get distributed afterwards with high manual effort.
Idea is to make it possible to allow constraints dependent from an attribute value. In our case we could use location specific enumeration lists and reduce complexity and administrative effort to update cascading attributes regularly.
Such enhancement would enable us to use cascading attributes and avoid conditional constraints (which bring disadvantages like during Import from Spreadsheet etc).