Alder Lake looks promising but i think delaying the release of PCIE 4.0/DDR4 motherboard chipsets untill 2022 is a blunder. I doubt early DDR5 is going to be either good, plentiful, or apropriatly priced vs good DDR4 when these initial SKU's release. In addition, PCIE5 is likely to significanlty increase the cost of the motherboards while most likely being pointless during the time period the platform will be relevent. I wouldn't be the least bit surprised to see the crap entry level stuff on z690 costing $250ish with more capable boards being well over $300. If TDP is also being pushed (requiring more expensive cooling) the platform cost is going to be way too high. Maybe this matters less when people are willing to pay out the butt for GPU's but I don't like the trend. Hopefully they at least keep the prices competitive on the CPU's even if they have a bit of an edge.
I haven't seen anything that suggests that z690 mandates DDR5 and PCIe5. Most boards probably will though.