Found this thread as I was just wondering this - or something related. A lot of countries have a fairly tenuous connection to the internet. For example a 72 year old lady with a spade cut off Armenia's connection to the internet back in 2011. When Elon Musk's constellation is in orbit, total internet outages will become much less likely but I can still conceive of scenarios in which the internet becomes fragmented (e.g. combination of solar flare and 72 year old lady) in which case presumably local Bitcoin networks would continue to be function independently until the connection was restored... at which point if I understand correctly how the blockchain works... things would become very messy and potentially this could become devastating to the reputation of cryptocurrencies.

It seems to me that this could be protected against in software e.g. if nodes refused to work unless they had access to a number of geographically distant nodes. Or the network could even continue perhaps if there were a way to send transactions over short-wave radio (probably not a good scenario for a solar flare).