[vanusa]

I'd argue the opposite, if the US government ceased to exist, the electrical grids in North America would collapse shortly thereafter, followed by the Internet and Bitcoin.

No, there will just be temporary outages and prices these things (electrical grids, internet) will rise to extortionist levels as local authorities / militias take over. Just like they do in any other conflict zone in the world.

[politician]

If a major superpower falls, adversarial superpowers will be the ones to move in to fill the power vacuum, not local tribal warlords. See Russia after the fall of the USSR, but before Putin.

[vanusa]

If a major superpower falls ...

I don't think you can say there's a general "rule" like this, throughout history. If anything the cases where these powers become straight-up subjugated from the outside (absent outright military invasion) are in the minority. Counter-examples abound, e.g. the Ottoman Empire and Austria-Hungary, or Spain after the disaster of 1898.

See Russia after the fall of the USSR, but before Putin.

Post-Soviet Russia was weak for sure, but not a vassal state by any interpretation.