In the long run the problem is self-correcting.

If workers can't afford to live in what were the important cities, they live elsewhere.

Eventually employers move to where the workers are. The formerly important cities become tourist meccas like Venice or Granada, or ghost towns.

This is happening to London and Lisbon, and to a lesser extent to Amsterdam, Paris, New York and San Francisco, and other cities.

It's a pity, because the famous cities got big early because they're in good places for trade. Their replacements are second best in this regard.