Say, we reach year 2xxx, and for some reason the transcontinental communications become intermittent like some countries have intermittent electricity right now.

What happens to bitcoin? At first, i guess no node sees the issue as long as nodes are connected to some miners on the same continent. Each area only sees it's own transactions and can validate them. The block chains evoles on one branch per area. But when the link comes back online, what happens? There is no 'merge' support. Miners will keep the chain branch they choose. I guess it's ok to lose a few <10 blocks occasionally. But what happens if we have diverged for 1000+ blocks? I guess each miners keeps building on it's own version of the chain in this case? Nowadays, we can assume that if a transaction has 3 confirmations, it has very little chances of being cancelled later. But if 1000 transactions can be cancelled, then we could not exchange it anymore for physical goods, as the physical exchange would have been long done before we are sure the transaction will not get cancelled.

Are there some plans to add som 'merge blocks', that would, remine the transaction of the lost branch that do not conflict with the main branch? I guess something like this might even not be wanted at all? Some people that have the private keys of the same wallet in multiple areas would cheat the system by strategically double spending some utxos

And what about lightning? Inter continental channels would go offline, and intra continental ones would stay up. Intuitively, it seems like the channels would have no issues as long as they don't try to do onchain stuff while the link is down (hoping internet interruption is always lower than force close delay...). But would it actually work? Currently, a node can be offline for weeks withous issue. It will just analyze what happened in the onchain blocks it missed, and resume chat with the other node to check state coherence. But what happens for the node that will have 1000 blocks of it's blockchain cut? WIll it be able to keep the channel in a stable state, with current lightning implementations? Or will all intercontinental channels need to be force closed eachtime a long internet interruption with lots of diverging blockchain occurs?

What are your ideas/opinions? Do some other blockchain take this into account?