Not just GPU but display bandwidth too, 5500x3000x120Hz requires a monstrous 59.40 Gbps according to this calculator:
https://k.kramerav.com/support/bwcalculator.asp
For that you'd need multiple displayport cables.
For that you'd need multiple displayport cables.
By the time GPUs able to render at this resolution and framerate become mainstream I'm sure we'll have the cables to connect them. The big problem with VR is that you want very long cables to be able to move around unless you manage to stuff everything into a backpack. Very high bandwidth and long cables don't always play very nice together. Worst case scenario there's always optical fiber...