The PCI Special Interest Group (PCI-SIG) has published proposals for the PCI Express 7.0 version 0.3 specification. The company will keep updating this data, but for now they tell us that a single PCIe 7.0 line will transfer twice the data of PCIe 6.0. The latest version, by the way, is twice as fast as PCIe 5.0 and so on. PCI Express 7.0 will appear in 2025, but not everyone has switched to PCIe 4.0 yet.
The current draft specifications will be circulated to all PCI-SIG participants for further development. One x16 PCIe 7.0 slot will provide throughput of up to 512 GB/s, by the way.