Every (at least most) past conflicts that toppled the dominant players brought with it a new type of combat that those players were not ready for. Troop tactics, air power, etc. In the next one, it will be cyber.

We have opened a direct line for all of our enemies to be able to attack us without any regard to geography whatsoever. Critical infrastructure is all online and barely protected by even the most basic security. We’ve already seen multiple utilities go down due to hacks, and those were probably accidents where the attackers were overzealous. It’s not unreasonable to assume that we’re already completely pwned, with foreign interests just sitting back and waiting for the right time to flip a switch.

Military and geographical advantages are irrelevant in this scenario.