some scenarios though:
1) confidence is completely lost somehow, the price drops to near zero, the miners flee ... but this is ridiculous. It only needs one miner and a couple computers (maybe) and the stuff will live, ready to rise again. The difficulty adjusts so transactions continue, mined by a toaster (with a disk, haha) if necessary.
2) a complete, worldwide ban. This is also ridiculous. There's no way that could stop it short of shutting down ALL communication between computers.
3) complete loss of interest: hmm, maybe. That would imply something better has arrived though. Something so much better that we all move, that we are happy to lose our current coins, that miners are happy to lose their hardware investment or that these are somehow leveraged. Fine.
4) bitcoin protocol design problems, unfixable: Hard to imagine given the open source nature of the beast, the years of testing already done, the determination of people, the stakes involved now ...
5) physical disaster, all blockchain copies lost: The sun supernovas AND the universe's entropy maximizes. I won't hold my breath
If I had to put money on it, I'd guess only (3) makes any sense.
Thoughts?
edit: oh crap. wrong forum.