Link between the filters - Automatic reduction of selection

Right now it is a nightmare to have subselections of filters. It would be a great feature if the system could automatically update the available choices in the filters once one is selected.

For instance, if you have a filter "Country" and a second filter "City", it would be great if once you selected country only the possible options would stay in City rather than the whole list of values existing in the entire library. That would avoid the need of multiple categories to create limited filters per option or the need of sublevels within categories which are a nightmare to set in place.