For a full 16-lane PCIe 6.0 connection, that's as much as 256GB/s of total bandwidth, compared to the 32GB/s or 64GB/s of now-common PCIe 3.0 and 4.0 connections.
Like past PCIe versions, PCIe 6.0 will "interoperate and maintain backwards compatibility" with all existing PCIe versions, so your PCIe 4.0 GPU or SSD will continue to work in a PCIe 6.0 slot and vice-versa.PCIe architecture has far exceeded that mark.".
Consumer systems are just beginning to support PCI Express 5.0—Intel's 12th-generation Core processors provide 16 PCIe 5.0 lanes, and AMD plans to support PCIe 5.0 with its upcoming Zen 4 architecture and Ryzen 7000-series CPUs.The PCI-SIG recognizes in its PCIe 6.0 FAQ that the new spec's bandwidth isn't necessary for most consumer applications, pitching it instead as an upgrade for data centers and artificial intelligence and machine learning systems.