I don't understand the first one but regarding the last two, isn't it extremely difficult and impossible to break ECDSA and Sha256 encryption? I am sure if there was some fault it would have been discovered long ago.
There is a little difference, SHA256 is not an encryption but rather a hash function which is a one way algorithm that is almost impossible to reverse because the computational power needed to actually is not something that can be done soon. ECDSA is an encryption algorithm, specifically an asymmetric algorithm which uses two keys which is the private key for encryption and the public key for decryption, this also requires a higher computational power to decrypt the original input.
But as science would have it, there is nothing that they see impossible, we have heard or seen other algorithms that were first developed to be impossible to be broken get broken. But this wouldn’t happen overnight so before it would actually poses threat to the algorithm (like this hash used today gets broken) we will would migrate.
Here is satoshi response to a hash 256 getting broken in future
SHA-256 is very strong. It's not like the incremental step from MD5 to SHA1. It can last several decades unless there's some massive breakthrough attack.
If SHA-256 became completely broken, I think we could come to some agreement about what the honest block chain was before the trouble started, lock that in and continue from there with a new hash function.
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.
