The world would be a much worse place without the US around.
There will always be an imperialist power to fill the void. And I can think of much worse powers than the US. Japanese imperialism, British imperalism, German imperalism, French imperalism were all worse. In terms of imperalists, Americans are relatively benign. If you think nobody would step up to seize power if the USA suddenly went isolationist or disappeared, you're naive. I'm sure everyone prefers America to the Empire of Japan.
It can get much, much worse. History is longer than ten years.