Have you watched the show 2057? Do you think that there will actually be 250 mile high space elevators by the year 2057? That is about 1,250 Empire State Buildings stacked on top of each other. If you exclude the ambitious towers of Dubai, the world has only built a freestanding structure of 533 meters, the CN tower. 1609.4 meters equals one mile. Is it really possible to build a 250 mile high skyscraper in less than 49 years?
I would think that the stresses put on any space elevator by wind and any geological events (such as earthquakes) would make it too expensive to build and stay around. Not to mention, how big would the elevator have to be to carry an economic load?
I highly doubt it.. ;/