AMD doesn't officially support Ryzen 1000-series (Summit Ridge) chips on the X570 chipset, but Asus has added it to its motherboard. The latest firmware, spotted via @Komachi, for the ROG Strix X570-E Gaming brings full support for Summit Ridge chips and the long forgotten Raven Ridge APUs.
The motivation for not supporting previous generations of Ryzen CPUs on some AMD motherboards comes down to the size of the motherboard's BIOS chip. With every Ryzen launch, AMD provides its partners with the corresponding microcode to get the new chips to work on previous motherboards. Eventually, the BIOS chips run out of space, and compromises are made. Motherboard vendors that foresaw this limitation wisely incorporated bigger BIOS chips into their offerings.
In Asus' case, the company endowed the ROG Strix X570-E Gaming with a 32MB BIOS chip, which is why the motherboard has the luxury of supporting three generations of Ryzen processors, plus the APUs. There are many other high-end X570 motherboards on the market that pack one 32MB BIOS chip or a combination of two 16MB chips, but those boards don't offer the same level of support as the ROG Strix X570-E Gaming.
It's unknown if Asus' BIOS chip will be large enough to support the Ryzen 4000-series (Vermeer) desktop CPUs when they come out. Asus might have to go back and ax support for some of the older models once those chips land.
A DigiTimes report from two weeks ago said that the 7nm Ryzen 4000-series' release date will be at the end of Q3 barring any setbacks.