Here I am still on PCI-E 3.0...
Most hardware (NVMe drives, GPUs, etc) doesn't run at more than 4.0 speeds anyway. The primary advantage of 5.0 and higher is that it'll allow that hardware to use fewer CPU lanes, eg what requires 4.0 x4 could use 6.0 x1.
It kinda worked that way in the past too. IIRC, newer AGP graphics cards would be keyed for 4x or 8x slots but would barely use more bandwidth than the original 2x slots provided.