The economic downturn in the US probably lends greater urgency to this US aim. Many Latin American rulers are reluctant to accept the US plans. Brazil's rulers, for example, are dealing with their own economic crisis and have ties to Mercosur and to Asian and European capital. It doesn't necessarily serve their capitalist interests to accept the US plans, although they will probably be careful not to oppose them to openly or aggressively. As James Petras wrote recently in an article in Z magazine, we should stop using words that were invented to obfuscate reality.
Globalization is imperialism.
Structural adjustment is wealth concentration and plunder. The formation of regional blocs is a symptom of the sharpening of inter-imperialist rivalry. The main danger facing workers everywhere is not that capitalists of all countries will unite. It is that different blocs of capitalists will compete economically and politically and eventually militarily, as they did on two notable occasions during the last century. Meanwhile, it is important for anti-globalization forces not to ally with one imperialist against another.