What would happen to Bitcoin’s value if all countries banned crypto exchanges together ? Can it survive such an action ?
This question would hold relevance many years ago when bitcoin was still very early especially when that mt gox hack happened and most recently, the FTX collapse. But since bitcoin didn't stop there, those events alone should be able to answer your questions.
Fwiw, even if exchanges are banned, there would be ton of decentralized solutions that would come into play.