It won't matter, IMHO. Every empire that ever collapsed left a transitional period of decline in its wake until the next vigorous one cast its umbrella of prosperity (if not peace) over its domain. The United States' empire is the largest, since it straddles the world - economically, not politically, although Canada and Mexico are very strongly encouraged to follow the US line on things.The US's military might buttresses the ability of US multinationals to achieve economic objectives. This is not a new phenomenon. Sosthenes Behn of ITT and later Harold Geneen often used the US State Department as a vector for their corporate policies even when their objectives likely compromised long-term US objectives or national security interests. All this was detailed in a book printed in 1974.
The only way the US State Dept. could have been manipulated like this is if the US's military were sufficiently able to exert force or the threat of force that other nations would not question why the US State Department was in such close contact with large corporations.
But now North America is dying. Economic and social tensions in the United States grow by the day; Canada's government no longer has the willpower to defend social programs except to placate basic fears that remain among Canadians about what Canada could look like if those programs were not there. Mexico's government is still prone to using its police and military officers to quell domestic dissent and is certainly in no position to do anything but throw up its hands if the US's imports from that country dry up.
As I have noted elsewhere, trends that existed in the USA in the late 1980s and early 1990s, if not staved off, would effectively turn the US into a Third World country by 2030. The vigorous expansion of the 1990s may have masked this, but the trends have returned.
So it is not an exaggeration on my part, I feel, to say that we are entering a new Gilded Age and are potentially looking at some elements of the Dark Ages (religious fundamentalism, economic feudalism in new forms) returning to western societies.