There were some pretty decent warning signs the British Empire was over, the American Revolution being a good one.

For the USD to collapse and not take the rest of the world with it, there would have to be some sort of global currency diversification that diminished the centralized power of the US in the global economy.

To continue the British Empire analogy, there would have to be some currency "revolutions" around the world. If the USD tanked, would Euros be able to replace it? Pounds? Yen? Yuan?

All of the countries tied to those currencies are heavily invested in US debt and many of their fortunes are tied to the US consumer.

That paradigm shift may be coming, but it seems like it's still a ways off to me.