Well then, this is troublesome.
Hopefully AMD's next-gen chipsets (ie: the AM4 4xx chipsets) maintain backwards compatibility with current-gen CPUs.
While AMD has been straight-forward about current-gen chipsets (ie: the AM4 3xx chipsets, A320/B350/X370) supporting all manner of AM4-compatible CPUs until AM4 is EOL'd, it is not yet clear whether next-gen AM4 motherboards will support current-gen CPUs. Probably not.