New Water LLC has a patented a "biodesal" technology (process, really) that puts salt-tolerant trees in floating greenhouses. As the trees suck in seawater from their roots, they transpire water vapor from their leaves. This water can be gathered and used.
Bottom Line: Necessity is the mother of invention, and water shortages are surely driving that process. (Of course, we could just raise prices, but that would be too easy!)