This is fair, but you're only addressing one vector of empire collapse, which is through warfare with external forces.
Empires and kingdoms have fallen through internal systemic failures, both political and logistical.
The modern prevalence of nuclear war has obviously all but removed the risk of collapse via invasion, but there are multiple other credible collapse vectors for the present day 'empires'.
Empires and kingdoms have fallen through internal systemic failures, both political and logistical.
The modern prevalence of nuclear war has obviously all but removed the risk of collapse via invasion, but there are multiple other credible collapse vectors for the present day 'empires'.