728 passengers per train on L0 trains vs 1323 on N700 trains, yeah it's lower capacity but it's a brand new line that's adding that much capacity, not subtracting from existing capacity. And they're already building it, and have been giving passengers rides on the test track for years.

Why would they be better off abandoning proven technology with construction well underway, costs very securely under control, and clear and strong demand, just because some foreigners balk at the cost and timeline? Like, this is Japan, they don't fuck around with this kind of stuff without damn good reason.

Also worth keeping in mind this speed puts the route in competition with air travel, in terms of cost and energy efficiency, so not only could it relieve some pressure from the Tokaido shinkansen but also regional airports.