The plan is to add a new control interface, and any new features will probably only work with that new interface, but the existing interface, including

The plan is to add a new control interface, and any new features will probably only work with that new interface, but the existing interface, including multiple hierarchies, will continue to be supported until it's clear that it is no longer being used. So they will support it forever or until such a time that devs do the 'right' thing instead of the quick hack, whichever comes first.