I think the primary implication in the "scare" stories is that areas which are running out of water to sustain their people are going to become de-stabilized and that will result in wars and civil insurrections.

Furthermore, the logisitics of moving large quantities of water around ARE immense, yes...but don't think that those logistics are not being put into place, because they are. Water is an absolute necessity, not a choice, therefore people will do anything they have to to get fresh water. Anything. You either get it or you die.