There is ConnextX-9 already which does 800Gbps in a single port. I am eagerly waiting for "Serving Netflix Video Traffic at ~~800Gb/s~~ 1.6Tbps and Beyond" from last time I posted it in 2022. [1]

[1] https://news.ycombinator.com/item?id=32519881

It'll be interesting to see if they leverage any new hardware features I've heard of in the past 3 years. One is AMD got the feature that allows PCIe to be DMA'd directly to L2|L3 working. Another is something about PCIe devices being able to talk "directly" to each other. Pretty sure it's actually mediated by the PCIe controller though.

Alas, this is beyond any level I expect to ever see 1st hand, so I didn't retain more detail than I've given.

Notably, ConnectX-8 already has 200G PAM4 for 800G as a single port - and uses it for Infiniband.

Looks like it is so because it pre-dates 800G Ethernet ratification...

Any idea what the RRP is on one of these cards?

I don't think there is MSRP. I guess the retail price will be $3000 if you are lucky to find stock for it.

https://www.shi.com/product/49769688/NVIDIA-ConnectX-8-C8180 (prev model $2,347)