PCIe Gen4
PCIe Gen4
It's clear that backward and forward compatibility is confirmed. A Gen 4 card fits in a Gen 3 slot and vice versa. The upcoming Nvidia GPUs will use PCIe Gen 4 connections. Certain motherboards, like the Z490, are already compatible with Gen 4 PCIe slots, though Intel hasn't released any CPU support for Gen 4 yet.
Intel hasn't reached PCIe Gen 4 yet, similar to the situation with 10nm. If some boards can handle it, we might expect Intel to bring it to the next generation of CPUs while keeping the same socket. This wouldn't really affect GPUs unless low-end models use PCIe Gen 4 x8, which would matter a bit—like the RX5500 XT if I recall correctly.