I don't think the elimination of cable losses is near the top of the list when it comes to discussions around why high temperature SC is revolutionary.
Stronger magnets! Better magnetic bearings! RF circuits.
If superconductors were feasible on integrated circuits, I'd expect the TDP to get lower, enabling higher frequencies and integration (3D?). Frequencies would still be limited by propagation delay, but we have some room to grow. Classic FET wouldn't work, I think, at least not without bringing back switching losses, but there's probably a way to create a magnetic transistor using a few superconductor wires (locally increasing resistance above 0, for instance). Or use FETs with adiabatic computing, who knows? Future seems bright, and applications for room-temperature superconductors are aplenty. It's just that everyone thought of them as a pipe dream, so they aren't really being investigated that I know of.
Superconducting computer will still dissipate heat, as there is minimum cost per element switch due to thermal noise. This makes superconducting computers more efficient at lower temperatures. Room temp superconductor would be cool for making research simpler though.
