ASRock issued a clarification about the Zen 2 support status of the AMD A320 chipset. The company indicates its A320 based boards will not support the upcoming Zen 2-based Ryzen 3000 series, they will only support the next-gen "Picasso" APUs.
That would follow the trend of BIOS updates we've seen from major vendors of late. The recent wave of updates has enabled Ryzen 3000 support for higher-end X- and B-Series motherboards, but support for A-Series motherboards has been conspicuously absent.
We still don't know an exact reason but it seems the upgrade path for these budget chipset based motherboards will be limited. So far, it seems A320 motherboards from other brands will not support the new Ryzen 3000 CPUs either.