According to the latest tweet from Patrick, Rembrandt would support DDR5-5200 memory and up to 20 PCIe 4.0 lanes. This would also be the first AMD APU processor series for a new socket, rumored to be AM5. The transition to a new socket will provide support for next-generation DDR5 memory.
AMD Rembrand is a codename for next-generation APU, planned for both desktop and mobile series. This is a Cezanne successor which is a successor to the current-gen Renoir itself. That said, we are talking about an architecture that is coming to new products probably around 2022. https://cdn.videocardz.com/1/2020/09/AMD-Rembrand-6nm-Navi2-2020-APU.jpg
late 2021 to 2022
2022 falls 1/2 way thru the block of rembrandt
socket changes.... no more AM4