V3 transaction policy for anti-pinning

[orangesurf]

@harding

it’s easy to turn those rules into consensus rules: a block may only include a parent ephemeral anchor if it also includes the child spend. We could also add an extra rule in the soft fork: the child spend must include at least two inputs. That would mean the amount of block space used by someone paying miners out-of-band would be equal to the (best and expected normal case) of someone paying any miner in a decentralized fashion. In other words, the incentive for paying out of band would be eliminated.

Is it a given that there would be widespread consensus for such a soft fork?