This planet is overpopulated with humans that threaten the ecosystem. It is time that mother nature fights back. Cities will disappear but fret not, humanity will survive.
For environmetnalists the best way to fight against environment destruction is 1st and formost to reduce the global population rate and not by eating organic food.
As for the major cities that could disapear, this include parts of Bangladesh, a nation that is overpopulated and where Islamic fundemetalism is rising.