OP_CHECKHARDFORKVERIFY - replay protection and fork futures on off-chain payment channels

Good morning list,

I would like to speculate on the addition of an opcode which would provide replay protection and allow chain-backed trustless creation of hardfork futures payment channels.

Note however that in order to work, the hardfork must "cooperate" by changing the operation of OP_CHECKHARDFORKVERIFY in the hardfork.

The opcode is simple. If the top stack is not the exact value 1, it fails.

The intent is that a hardfork must "cooperate" by also changing OP_CHECKHARDFORKVERIFY so that the top stack must be some other, non-1 value after the hardfork date. This is a consensus break, but as a hardfork is defined by the fact that it is a consensus break, this is deliberate.