I'm aware of governments (or other situations) leading to a temporary shut down of their internet, that's why I said permanently.
If it's temporary or limited to a country, then bitcoin doesn't really suffer much from that either. The blockchain will continue elsewhere and can be synched back up for your region later, or if it's everywhere, then it will just stay in a frozen state until the internet is back.
So you can go to a country where there's still internet (assuming you can, you might not be able to), or wait until the internet is back up.
Hopefully you have other assets or goods to get you by in the meantime. Bitcoin is too volatile for it to make sense putting all of your wealth into it anyway.
Lets assume a state-sponsored threat model, with AS blackholing. It may happen the node you connect to sparsingly to sync your ledger is a malicious one, and does not represent the main ledger.
Lets assume you are in a country at war, with poor conectivity and you receive money via blockchain; Poor conectivity means the local places where you can spend your virtual money aren't synced, possibly for weeks. What good is for you money you can't access?
There are far better ways of carring value in warzones. Crypto currency is the most useless one - specially because you can't easily bribe anyone with it.
Imagine having to awkwardly sit there with the person you're trying to bribe while you wait for your transaction to synchronize. This is where someone says something about L2 or whatever, usually.
If it's temporary or limited to a country, then bitcoin doesn't really suffer much from that either. The blockchain will continue elsewhere and can be synched back up for your region later, or if it's everywhere, then it will just stay in a frozen state until the internet is back.
So you can go to a country where there's still internet (assuming you can, you might not be able to), or wait until the internet is back up.
Hopefully you have other assets or goods to get you by in the meantime. Bitcoin is too volatile for it to make sense putting all of your wealth into it anyway.