Not so sure that Datacenters will be using this anytime soon, I have all the latests pre-production samples of everything that will be shipping in a few years from all the major mfgrs and it is pretty hard to saturate even the standard 100gbE Mellanox cards, let alone the 400gbE ones.
For example, currently Microsoft is only using 2port 100gbE in their cool custom Azure blade servers.
something like this will probably require pcie 12 which has not even been considered yet

Just imagine the infinite security keys that can be created with this...................
PCIe5 was hard enough to get working reliably.