They have no reason to exist so fill up with non whites. Look at the whites remaining in any cities in the US. They produce nothing beyond pushing paperwork back and forth between each other. They have no skills and produce no products most of them work in service labor positions or pushing financial instruments around or work for the government enforcing and endless list of meaningless regulation to prevent capable people from doing anything. Without industry no skills are reinforced or practiced and no advancement is made because those things are downstream of the practice of manufacturing complex products and ideas. You cant base a city off fine dining and food trucks or lawyering or doctoring. Tangible goods production and developing a highly capable intelligent populace from industry are what builds cities. As soon as the industry stops the system eats itself. Smart people leave and go elsewhere where their skills are in demand and the cost of living is cheaper and they can be around other skilled people and be less reliant on a system that is cannibalizing itself. The politicians of course think they can just replace those people with the third world but they can't and they inevitably turn into the third world hell holes we see now.