This might have belonged here better.
My main point of this post is discussing what we find OK and what not. I can create a contract which changes behavior if an unoccupied opcode in the past is occupied at a fork. Do we now assign all these opcodes as INVALID because a single contract suddenly changes behavior? Probably not. But what if there is 10% of all Ether in it? Can I hold the network hostage against forks via this?
Constantinople is delayed because possibly many contracts are affected. But what is the minimum amount of affection a fork may have to delay the fork?