It should be noted that under the current system for organizing international electricity trade, a gold mine is exactly what this is - Denmark does exactly what is proposed here already, and while the net trade in kwh sums to near zero, the net trade in kroner favors the storage vendors. A lot.

Selling timeshifting is currently a heck of a lot more profitable than selling intermittent electricity is,

- Jake

Friends come and go. Enemies accumulate.

the net trade in kroner favors the storage vendors. A lot.

And there's typically a profit-sharing arrangement in place between both nations

investment in intermittent generation capacity appears to be running ahead of investment in grid and storage quite badly

Errrm, no.  Investment in grid storage was there decades before the investment in wind and solar.