Subject: An Onchain Implementation Of Mining Feerate Futures Introduction Future onchain fees to be paid to miners cannot, in general, be predicted, as unpredictable novel uses of the blockchain may increase use of block space, and unpredictable novel innovations on block space use reduction may decrease use of block space. This uncertainty makes onchain use unpalatable, and even non-custodial offchain uses like the Lightning Network incur risk of onchain enforcement, and the uncertain onchai...