There may be a loss of interest or focus, often related to technological changes causing an atrophy over time, but that usually also just leads to long tail existence that seems to mostly be defined by the duration of the career length of those involved and/or any kind of special interests that can maintain their nepotistic/corrupt advocacy.
It is a function of the empire and the reserve currency status of it, i.e., the “infinite” money printing that causes profligacy that is also an existential threat because it distorts perceptions and reality, e.g., the belief that it does not matter and that no discipline in spending or budgeting is necessary, hence why America has essentially for 56 years now (ignoring the anomaly in 2001) not produced a balanced budget.