Bad news for owners of an AM4 motherboard with a 300 or 400 series chipset: AMD confirmed that the next Zen 3 processors will only support the X570 and B550.
That may sound bad news, but let us remind you that AMD also said that the Zen 2-based Ryzen 3000 would not be compatible with the 300 series, but the manufacturers still gave support. This gives us hope that they will at least add support to the 400 series, although this depends on the individual manufacturers and how strictly AMD follows their rules.
Another important piece of information revealed by AMD is that the Ryzen 3000 APUs (3200G and 3400G) are not compatible with B550, nor will all Ryzen 2000 and Ryzen 1000 processors, so this chipset will only support Zen 2-based Ryzen 3000 and future Zen 3-based Ryzen.
It will be interesting to see what the manufacturers are doing, as this is the minimum required by AMD, but the manufacturers can extend the compatibility if there are no technical problems that prevent this. We will know this once the products are on the market.