Would Bitcoin survive through offline solutions like mesh networks and satellites, or would it completely halt?
Very likely that it will still exist. The internet shutting down won't completely erase the bitcoin network so, it will be stopped for a moment but will remain there.
That's why even if there will an internet interruption for a week. Transactions will be stuck and it will be back once again if any of those mesh networks or other solutions will make it back there to proceed.
Satellite technology is already there and it's not only Elon's starlink provides it.
Bitcoin will always be there either network or not , in as much as Bitcoin is still available it is not yet exhausted, it is the network that will only be affected not bitcoin, it just like when you cannot access it due to the nature of weather or your accessories goes bad and prevent you from getting through and when you are back Bitcoin is still there waiting for you. No internet, no bitcoin transaction but bitcoin exist
Bitcoin has already being programmed, so if network is not available whenever it comes up it's there, but remember that Bitcoin works only through network that is it only exist as in the bitcoin blockchain and needs network for you to be able to access your data.