This is exactly the reason why people started living on houseboats in the canals of Amsterdam. It was a lot cheaper than the ever rising house prices. However, at some point the city council smelled a new opportunity and introduced fees that house boats had to pay for the right of anchoring somewhere. Later came 'roerende ruimte belasting', a tax similar as for house owners, garbage taxes etc. And now houseboats cost as much as normal houses or even more.

I guess in these US cities the end result will eventually be the same.