AMD is about to usher in the PCIe 4.0 era with its new X570 chipset (and the purported even higher X590 chipset) alongside its next-gen Zen 2 CPU architecture and Navi-powered Radeon RX 5700/RX 5700 XT graphics cards, and now we're hearing about PCIe 6.0.
Yes, PCIe 6.0 - the successor to PCIe 5.0 which we should see Intel adopt in late-2020 and more 2021 and beyond, will roll out with an incredible amount of bandwidth. PCI-SIC, the group behind the PCIe standard said that PCIe 6.0 will have up to 64GT/s of bandwidth providing a PCIe 6.0 x16 slot up to an incredible 256GB/sec of bandwidth.
This is double PCIe 5.0 x16 with 128GB, and 4x the speed of PCIe 4.0 x16 which will provide 64GB/sec. PCIe 6.0 is a gigantic upgrade on our current-gen PCIe 3.0 x16 slot with just 32GB/sec of bandwidth in comparison, to the upcoming 256GB/sec on PCIe 6.0 x16. We most likely won't see consumer graphics cards taking advantage of this, but storage eats up a lot of those PCIe lands and future networking technology and AI accelerators will definitely chew it up.
The state of the market right now is that PCI-SIG set the PCIe 5.0 standard in May 2019 and "compliance testing is under development" while PCIe 6.0 is "targeted for publication in 2021".