Im not following you... Showcase has always used a hierarchical category system (same as XFRM categories), so you can have sub categories, sub sub categories sub sub sub categories etc..
North America
>> USA
>> >> Texas
>>> >> >> Dallas
When viewing the North American Category, its going to display all items in North America, USA, Texas and Dallas. When viewing the Texas cateogry, its going to display items from Texas and Dallas.
If you add an item to Dallas, the breadcrumbs is going to be Showcase >> North America >> USA >> Texas >> Dallas
This is a standardized system in XF2 now (in XF1, each addon had to build its own, however, in XF2, there are controller helpers, functions, macros etc that addons (to include XFRM and XFMG both use).