With everything Rocket Lake processor awaiting in the processor pipeline, we already know that the current Z490 motherboards will support the new processors, but wait, Dave, there's more.
Of course, Rocket Lake will finally open up PCIe Gen 4.0 to the infrastructure. And Z490 would/could be compatible, but knowing Intel, it's wont as they love to release new chipsets to boost their sales. New motherboards based on Z590, B560, and H510 chipsets thus are inbound, nothing new, of course, but they haven't been really confirmed either. Well, they're coming as the new logos got leaked over at videocardz.
Rocket Lake-S (the desktop parts) are expected to offer 4 supplementary PCIe lanes, which can be used for direct CPU<>NAND NVMe PCIe 4.0 storage. Z590 and B560 chipsets will both support PCIe 4.0 x16 for discrete GPU, something that AMD is now offering for two years already.
We're interested in Rocket Lake-S for sure; however, the 500-series motherboards will not be around for long. As later this year, Intel will announce Alder Lake, which is to feature an LGA1700 socket. Rocket Lake is LGA1200 ergo, and the motherboards will not be compatible.