What would happen to Bitcoin’s value if all countries banned crypto exchanges together ? Can it survive such an action ?
In a perfect world, it is technically and fundamentally not possible! So I wouldn't think too much on this.
But for argument if I consider that all countries banned crypto exchanges and implemented punitive measure for crypto users, Bitcoin’s value would drop sharply in the short term — possibly catastrophically. But it wouldn’t go to absolute zero unless the network itself was shut down. Now this part is technically much harder and almost impossible.
So impact will be there but Bitcoin wouldn't die immediately.
Do remember, each country has their own free will regarding this, so I don't think all countries would just ban crypto. Because the more realistic situation is that, one or several countries may ban but not all.
So the discussion I guess, is pointless. We will only be talking about theoretically here.