After Asus and Gigabyte initially gave no hint regarding B350 chipset support for Ryzen 5000 CPUs, the former has now apparently confirmed that the chipset will be supported alongside A320 and X370.
B350 chipset RSS
While AMD made it official yesterday that first-gen Socket AM4 300 series chipset boards will support the new Ryzen 5000 and 4000 CPUs too, there appears to be some major caveats, at least for now.