Rome was a notoriously unhealthy place to live in the middle ages. The surrounding countryside was depopulated in the disasters of the late Empire, and a lot of the farmland reverted to malarial swamps.
Certainly - it had its ups and its downs, but continued to be somewhere, and still is now. I would bet on it still being somewhere in another 2000 years.
My point is that housing technology is nothing compared to demand for good locations in terms of its affect on prices, and good locations have a lot of staying power.
BTW, those marshy areas in Lazio have been fairly marginal for a long time:
