Quote from: Pieter Wuille on February 19, 2013, 04:04:17 PM

In a hard fork, it is about getting _all_ of _everyone_ to change the rule at exactly the same time. Doing a hard fork where not everyone is on the same side, is an outright disaster. Every coin that existed before the fork will be spendable once on every side of the chain. If this happens, it is economic suicide for the system. Sure it may recover after a short while, when people realize to pick the side that most others chose, but it is not something I want to see happening.

This isn't a hard problem to solve at a technical level. Have the nodes keep track of the version numbers they see on the network. When X% of the network has upgraded to a version which supports the new rules, and when Y% of the miners indicate their support via coinbase flags switch to the new rules. Until then use the old rules. Let the users decide when and if to switch.