It looks like ASUS has slipped up and leaked Intel’s upcoming Z490 board ahead of the official launch. The product page for the ASUS Prime Z390-P shows the product details about its successor, the Z490-P instead of the former.
As you can see, most of the specs are identical to the Z390-P. The primary chance is the new LGA1200 socket. Memory has been upgraded to support 4600MHz DDR4 in OC mode. The M.2 and SATA capabilities are unchanged with 2 and 4 ports, respectively. USB 3.2 Gen 1 has also been added with four front and two back ports. Furthermore, there are two USB 3.2 Gen 2 ports on the back as well.
Overall, the Z490 boards are looking to be an incremental upgrade over their processors, much like the Comet Lake-S processors themselves. The official announcement is slated to come on the 31st of April, followed by a hard launch in May. The prices are expected to be the same or slightly higher than the 9th Gen Coffee Lake offerings.