Late 2020 is the latest rumor based on AsMedia's X670 chipset, but depending on AMD's direction with DDR5, USB 4, and other such tech, there's a real possibility it won't be until 2021. More concrete information will probably come out around June.
Ryzen 4000 processors are being allocated to the channel. NewEgg etc should have them for purchase by June. I have been accumulating funds for a better CPU but the 3000 series have issues I want to avoid.
As for a new chipset, hopefully it is better than the dodgy X570
