I mean if we have two different chains then it's two different chains, we cannot have two different networks and then call it the same thing. Meaning we could have unlimited number of networks not just 2, but they won't be the same thing and this is where the problem starts.
In the event of an internet split, then it is entire possible to have two different chains which are both called bitcoin. They would both be running the exact same code, and as far as each node is concerned, would be following the consensus rules by following the chain with the most proof of work (since they are unaware of the alternative chain). And the same thing could happen 3, 4, 5, or more times. Each independent network would still be running bitcoin as far as they are concerned. But as discussed above, we already have a mechanism in place to resolve such a split when the networks rejoin.
Interesting enough, in the event of a global internet outage big cities and suburbia will probably have a much better time of it then the middle of nowhere. With most of the large data centers in populated areas it would be easier for them to get access back to the people close to them, then someone living in the middle of a farm 200 miles from nowhere.
True, but in a global internet outage supply chains collapse almost immediately, so I'd much rather be living 200 miles from anywhere with my own back up generator, clean rainwater collection system, and land for growing food, than in the middle of a heavily populated city which would quickly break down in to constant riots, looting, and violence, over the quickly diminishing supply of food and other essentials.