>>343002908
The cables are a custom mix of usb3, power, and display port. I don't know if they're strictly proprietary since there is/was one third party cable maker, but you don't get the economies of scale for manufacturing. It's a shame the VR link standard died, or we would have cheap USB C replacements instead. 

You can baby your cable a little bit, but I think it's a better strategy to go hard the first year and get as many RMAs as you can (cable, controllers, and headset). 

Index is 2 year old hardware now, so maybe valve will do a refresh this winter, but they might also be fucked by supply chain issues, plus general valve time issues. Back before the index was announced I was really pessimistic on the rumors of them releasing their own headset at all though, so they might surprise us.