Earlier quoted context omitted.
“A 1,100 kV link in China was completed in 2019 over a distance of 3,300 km with a power of 12 GW.” Which is rather close to your example. By comparison a major gas pipeline runs around 8 Million dollars a mile or ~16 Billion over that distance meanwhile that link cost under 6 billion USD. Granted our construction costs would be higher, but it’s not the kind of massive savings that changes the equation much.
In that case how far are we from being able to supply all US electric needs with solar ? I think I've heard that with current solar cells you could produce that much power with a 100 mile x 100 mile installation in a sunny location. If battery storage and power transmission are solved problems, are the obstacles now only economic ?
IMO, we are headed to about 70% renewables in 30 years baring major changes.