If we are going to stay in the capitalism race, we will probably have to take all of south america by force and enslave the whole population.
This is very very difficult. Firstly, you would have to do massive geno (i d. 2nd, You'd have to achieve full totalitarian control the the US first.
Chances are, Our own Civil war is more likely than accomplishing the takeover of South America.
Not undoable. Just very very hard.