Satoshi: If the hash breakdown came gradually, we could transition to a new hash in an orderly way. The software would be programmed to start using a new hash after a certain block number. Everyone would have to upgrade by that time. The software could save the new hash of all the old blocks to make sure a different block with the same old hash can't be used.
It seems to me that we are at such a juncture that a set of 5-10 credible proposals should be collected, discussed by the developer community, agreed feasible timelines for each, then set a block number by which a solution should be implemented and users should have migrated.
It's not necessary that old addresses stop working, but spending from them should become incrementally more expensive, until they are drained by miner fees. If they are never moved then they are left as a quantum bounty, like Satoshi's coin.
If there are hard forks because no consensus on the solution can be reached then so be it, multiple solutions, let the market decide on the best one.
https://bitcointalk.org/index.php?topic=191.0
It seems to me that we are at such a juncture that a set of 5-10 credible proposals should be collected, discussed by the developer community, agreed feasible timelines for each, then set a block number by which a solution should be implemented and users should have migrated.
It's not necessary that old addresses stop working, but spending from them should become incrementally more expensive, until they are drained by miner fees. If they are never moved then they are left as a quantum bounty, like Satoshi's coin.
If there are hard forks because no consensus on the solution can be reached then so be it, multiple solutions, let the market decide on the best one.