Citing a Chinese-language report, WCCF Tech reports production of AMD's B550 and A520 chipsets is expected to start later this quarter. These chipsets will enable motherboard makers to make less expensive motherboards for AMD's latest Ryzen chips. This market is currently served by the X570 and previous-gen chipsets like the X370/X470, but there's demand for cheaper boards as the X570-based models are pretty expensive.
Actual product availability is expected around Computex in June but there's still some uncertaintny about whether the B550 will support PCI Express 4.0 or not.
Computerbase has further reported on this and talking to their sources, it was revealed that the ASMedia roadmap is targetting the availability of B550 chipset-based products around Computex. It is expected that the use of PCIe 3.0 which offers more than enough bandwidth for this market tier and no extra chipset cooling would lead to more optimized costs than what we got to see on the X570 series.
In the second half of 2020, we can expect the AMD X670 chipset, which will expand PCI Express 4.0 support.