Because difficulty does not adapt dynamically, if the miners do not move then the fork will be defunct because it will take literally days to weeks to mine a block, and to mine the 216 blocks that would trigger a difficulty adjustment would also take proportionately longer. So transactions would sit in the mempool and the currency would be mostly useless.
replyFair point. Maybe you could hardcode a lower difficulty in the fork for the next couple dozen blocks, and schedule an adjustment after that?
replyAgree. Bitcoin is more of a social concept / weighted democracy than an algorithm. If the participants decide that a new / incompatible hashing algo is needed (e.g. post quantum), it will be forked and everyone will use that.
replyThe odd part is, the governance model is not defined. At the end of the day, some person or group has to decide what the new "real" Bitcoin is and the average holder just has to go along with it.
I think for most bitcoin users, the main usability concern wrt forks is being on the most secure chain; i.e. hashpower. If you're willing to trade being on the most secure, most historic chain for specific technical features then you're probably on an altchain already. In practice every hard fork in history the chain with the most hashpower has retained the ticker, meanwhile the users are never organized enough to do anything but follow that decision.
reply> every hard fork in history the chain with the most hashpower has retained the ticker
replyThe opposite is also true – most miners have stayed on the “official” chain :-) I do agree that having more hashpower helps, but ultimately all users (including miners) determine the price on the market.