Actually, what happened was that Britain’s role in the world and the sterling were supplanted by a larger and more powerful country and currency — the US and the dollar. In addition, after WW I, Britain disastrously returned to the gold standard at a value that aimed at protecting accumulated financial wealth but that its economy could not sustain. The result was continuing weakness in business activity and employment that evoked additional pressures against the sterling.
And that will never happen to the USA, yes?