Once the initial excitement/novelty wears off people from the surrounding suburbs/communities will find it more difficult to shop/visit/etc in the city and revenues will drop.

As a result, businesses will move to the outskirts so they can make more money, making living in the city more difficult (and thus less attractive). So people will move outwards as well.

This will leave the city center either desolated or turned into some sort of historical site or park.