However, this is for relatively low-end systems, with a couple of fast SSDs providing around 20 GB/s throughput (or with a few more, but connected through relatively slow Thunderbolt, for a similar total throughput).
If you use 16-lane PCIe add-on cards with 4 M.2 slots for SSDs and a total throughput of 50 to 60 GB/s, you can quadruple the previous speed in a desktop PC where you use the GPU PCIe slot for SSDs (a fast CPU, e.g. an AMD 9950X, would be alone fast enough for inference limited by SSD throughput, so a discrete GPU would not be required).
If you have a server/workstation motherboard, e.g. with 6 16-lane PCIe slots, you might gain another factor of 4 in the inference speed, so one might reach around 15 tokens per second for a very big model, but the cost would also be high, with so many SSDs, even if at that number of SSDs each SSD could be the smallest that can be found with a PCIe 5.0 interface.