AMD is apparently planning another chipset for Ryzen 3000. The X590 chipset is supposed to place itself above X570 and probably offers more PCIe 4.0 lanes.
AMD has confirmed that there is no PCIe 4.0 for old motherboards. In the run-up there were hints that X470 and B450 with Ryzen 3000-CPU can handle PCIe 4.0.