All empires collapse eventually.

Past performance isn't a guarantee of future results. With modern technology, the next empire will never collapse.

Until it does.

The heat death will guarantee the collapse of all and any empire.

All except the last.

OK, but England maintained Australia for centuries. Spain maintained the New World for centuries. I'm not sure "eventually collapsed" is proof that "it didn't work".

I mean, the Soviet Union eventually collapsed, and that wasn't because of communication delays. Everything eventually collapses. But "stood for centuries, despite the communication delays" kind of disproves the hypothesis. (Or if it doesn't, given the things that collapse after centuries without the communication delays, it means the hypothesis has no predictive power.)

The same argument could be made for Great Britain and the United States as well since the colonies were a part of GB for centuries.

I think the same argument for Canada applies to Australia: there must be a critical mass of well weaponed insurgents before the time delay makes too much of a difference.

Pretty much anything happens eventually.

Dinosaurs lasted 179 mil. years. The Roman state, between one and two thousand (depends on how you count).