This comes a bit earlier than AMD had originally indicated, and also includes the resizable BAR for use with RX 6000 series GPUs. X470 owners can now get all the benefits of the X570 boards minus PCIe 4.0 of course. Great news! Other vendors should be following soon if they haven't already.
Seems like Asus updated several ROG 400 series motherboard with the new BIOS to be compatible and support the 5000 Series processors.
Another User who opened a thread asking about whether his Asus 400 series will support the new generation CPUs and found that under the latest BIOS (12/2020) it mentions support for new CPU. But in his Motherboard's CPU SUPPORT LIST it hasn't been updated yet to show which 5000 Series CPU are compatible. It only shows 3000 series and below CPUs.
NOTE: Seems to be the same BIOS Version for his ROG 400 Motherboard also.