See https://github.com/lazyledger/lazyledger-specs/blob/master/specs/data_structures.md#feeheader for the type changes and https://github.com/lazyledger/lazyledger-specs/blob/master/specs/consensus.md#blockheader for the app changes.

This crosses the ABCI border as far as I understand. So we first need to clarify how the parameters will be communicated back to tendermint.

This work should start with an ADR.