Bryan, I expect the tether to outlast me. This isn't my design, I simply copied all the other manufacturers who use wired tethers including MTH themselves who use the same one on their diesels and its just about the same length. The actual conductors are small and made up of very fine individual strands. It should tolerate a lot of flexing before it breaks. Frankly, I never understood why MTH used the big loop on theirs. Your choice to try this might depend on your minimum curve diameters. Except for some of my switches mine are 072.
Pete, thanks for your insight. Yours is the same as what I thought. With O-72, the lateral flex is likely minimal. And if not after a period of time and with a part number, put a new tether in again. I like your idea. Thanks for posting and the pictures.