Bitcoin will exist as long as there's one or at least few computers running a bitcoin full node. What could possibly stop this? Probably a global blackout or a huge EMP(electromagnetic pulse)[1] or something.
Even if an EMP hit or a global blackout occurred, wouldn't that only be a temporary halt in activity? I don't think this would be the death of Bitcoin, unless I misunderstand something the blocks should just pick back up with extremely low-difficulty once we get power back.
I'm really not 100% sure, but yea I do think it will only be a temporary halt. What I think is though, that EMP can actually destroy electronic hardware, not just sort of crash/stop them like when a blackout occurs. Though it's probably unlikely for an EMP to destroy 100% of the harddrives of the whole world.
EMP interference is generally disruptive or damaging to electronic equipment, and at higher energy levels a powerful EMP event such as a lightning strike can damage physical objects such as buildings and aircraft structures. -Wikipedia