Wait, so we don't get a full-size PCIe slot? The proper one, for a video card? But how did Razer do it, then? And where does that spare 8Gbps come from? I mean, the 40Gbps max bandwidth is already stuffed with 60Gbps stuff... And the way it's implemented, I believe you can't connect everything at once, because you'll max out the bandwidth. Something like a USB hub: you still get maximum bandwidth of one port to share across all your peripherals. Anyway, if we include those USB ports, then it wouldn't use up the bandwidth if not used (taking into account the above calculations you did).
The only thing I'm curious about, is then how did Razer squeeze a full-size PCIe slot with enough bandwidth for a video card?
This shows that most games don't use as much as 4 lanes of PCIe bandwidth. So there's nothing to worry about as long as the physical connector is x16