This really is the right idea. Screw batteries, this is acheiveable today and outright fixes all the issues with solar and wind as the only required source of energy humans will need.
Not sure how this could work geopolitically. You need to able to build it to prevent a country from having the ability to hold another country hostage by cutting another country out of the network.
very very high costs, and although not horrible still comparatively significant efficiency losses, now when we get some superconducting wires