I wonder how expensive shipping brine would be… Probably very until we can get it ludicrously concentrated.
But then I imagine we could take it somewhere like the middle of an uninhabitably hot desert and just fill up a low point in the topology. The combination of distance from where people live and dry hot conditions drying it out as fast as possible would possibly work?
It wouldn’t be worth it unless shipping the brine was cheaper than just shipping clean water from places that have it to places that don’t. But who knows.