A list of upcoming ASUS motherboards based on the Intel Z690 chipset hit the radar on the Euasian Economic Commission (EEC) website, and it's telling. Intel's upcoming "Alder Lake-S" 12th Gen Core desktop processors support both DDR5 and DDR4 memory, as they form a point of transition between the two memory standards. The company's 6th Gen Core "Skylake" technically supported DDR3, helping people move between it and the then new DDR4, but motherboard vendors mostly avoided DDR3 slots. This time, the stakes are different, as component prices are on the boil, and the company would want to avoid placing the additional burden of new memory on people with DDR4 memory kits. This reflects on the ASUS motherboard lineup.
The lineup consists of the usual, predictable list of ROG Maximus, ROG Strix, TUF Gaming, Prime, and ProArt series SKUs, but what's noteworthy is that many of these come with the extension "D4," denoting DDR4 memory slots. For example, something like the Prime Z690-A comes in two variants, the standard one with DDR5 slots, and the "D4" variant with DDR4. It's interesting to note here, that the top-of-the-line ROG Maximus XIV series lacks any D4 variant, which means they'll remain DDR5-exclusive. We can't tell just from the names whether any of these models features both DDR5 and DDR4 slots; but one can definitely expect other brands such as ASRock to come up with such crazy contraptions.