There Goes the Neighborhood

So I've been thinking (an it was an assignment topic anyways) about the invasion of the Americas by the European forces, and all of the horrible things that happened to the people already living here. I mean, what with the diseases (as in smallpox and hemorraghic fever) and the slavery and systematic extermination of the local population, this really would be a "there goes the neighborhood" type moment, as in "Oh my! Half the neighborhood's gone, a.k.a. dead!". In fact in some areas, the entire native population was wiped out in just 50 years. Then, of course, you have the toppling of once-mighty civilizations and empires that had stood for hundreds of years. I sometimes wonder what would have happened if the europeans had never discovered the Americas. Would overcrowding turn Europe into a heavily crowded mess of cities with barely any space in between? Would the Aztecs mount expeditions across the Atlantic and find huge megalopolises taking up all of the space, with barely any room in between and a huge income disparity? Would European nations go east to Russia or China?

Ah, I love alternate universe scenarios....

- Noah