Minor nitpick — "now we can run 1 billion amps at 100V" — there is a limit to how much current you can put down a superconductor. For example I think commercial YBCO superconductor tape will do roughly 1000A/mm^2 (and even that requires being significantly below its critical temperature).

That’s a pretty high current density compared to what’s feasible with copper — don’t get me wrong — but a billion amps would still require a pretty huge cable even with a superconductor.