[wtallis]

In the server market where the extra bandwidth is actually useful, the transition from PCIe 3 to PCIe 4 is pretty far along. Switches, NICs, SSDs and FPGAs supporting PCIe 4 are all either available or announced, and server-class GPUs should also show up next year. Most of those products have good reason to continue on to PCIe 5 as soon as suitable hosts are on the way.

[floatboth]

Server-class GPUs kinda showed up first, or at least at the same time: Radeon Instinct MI50 was the first PCIe 4 GPU ever. (The consumer Radeon VII is the same chip)

[wtallis]

Ah, I forgot about that one. Possibly because they didn't enable PCIe 4 functionality on the Radeon VII.