AMD's Ryzen 4000 and Q3 2020-bound desktop processors confirmed to support the AM4 socket and B450 chipset
With AMD committing to the AM4 socket until 2020, the Ryzen 4000 series was not necessarily guaranteed to be compatible with existing Ryzen motherboards. Slated for release in September, the Ryzen 4000 desktop series is based on AMD's Zen 3 microarchitecture. Codenamed Vermeer, the processors are apparently based on an improved 7 nm process manufactured by TSMC.
However, XMG has now confirmed that Ryzen 4000 desktop processors will support AM4. Stated in a thread on Reddit, the company effectively stated that its APEX 15 will be upgradeable to AMD's upcoming Zen 3 processors. Presumably, Zen 3 will be the end of the line for the ageing socket. However, this would be considerably longer support than Intel offers for most of its sockets.
The B450 chipset will support Ryzen 4000 desktop processors, too. Released over two years ago, XMG states that B450 motherboards will receive a microcode update to support the Ryzen 4000 series. It remains to be seen whether all motherboard manufacturers will issue this update, though. Nonetheless, we would expect the X470 and X570 chipsets to support the processors if B450 will.