What do you mean by this? Cities in North America tend to be on rivers, and isolated poor location choices (Las Vegas, Phoenix, a few CA cities, etc) don't translate to problems in other cities since they are on different aquifer. As far as I can tell, there is no threat to the water supply in most American cities. Egypt/Ethiopia's little water spat doesn't threaten water supplies elsewhere, fresh water isn't really a commodity like oil or iron is. If it was, there would be a killing to be made in fresh water arbitrage.
Many cities are facing water shortages. Not just Las Vegas and Phoenix. The Colorado is tapped out, and California, Arizona, and Nevada have been fighting over it for decades. Rainy humid Atlanta was facing water usage controls for several years around 2007-2009. The Floridan aquifer is tapped out--developers are having to dig wells 1,000 feet deep these days to get water. Fracking is in danger of contaminating the Ogallala along with all the water that makes agriculture possible in the breadbasket. San Francisco is not yet in dire straights but Hetchy-Hetch isn't immune to the water problem.
For comparison, water today, where I live, costs slightly under a dollar per cubic meter. So even if my calculation was off by an order of magnitude, desalinated water would be a reasonable option for all US households, well under other budget items like cost of food.
Industry that depends on cheap water might be different, but how much of that is stuck in places without good water supply?
I'm not trying to suggest that if normal sources of water magically disappeared then things would be okay. I'm just saying that under possible circumstances there won't be any reason to fight to the death over water. Because of the desalination option, water shortages wouldn't be able to threaten anyone's life, only force businesses to adapt or move.
Also according to http://www.waterfootprint.org/?page=files/Animal-products even without any efficiency improvements caused by high water costs, pig would be $3 a pound more expensive and cow would be $7 a pound more. Easily afforded.
With such speculation, I could have a premonition of an alternative future where the initial settlers near all freshwater die, as the more aggressive and desperate peoples fight for the area, and this potentiality has as much merit as yours.
Also, why even say Detroit will come back if the original inhabitants are all but gone, and the area has been resettled by others? If Detroit's coming back in 2045, then [insert any maritime city/town/village/location/space] is too!