How can Chicago's city population be over 3.5 million again????

Two questions: Can it? If so, how. Of course, this is without changing the current boundaries of Chicago, not landfilling the lake or rivers, or bulldozing any the parks, beaches, and airport. ___________________________ To me, I think Chicago can, by building up way more skyscrapers in the Lakefront and rebuilt the southern and southwestern part of the city. Edit: Poll should say "CAN Chicago's city population be over 3.5 million again????">