blockchain history is not really needed...
it isn't? So how do you verify supply? actually I should have asked - how do you know you have a valid utxo set? The whole point of downloading and validating a chain is to get a valid utxo set.
Consensus perhaps need not be confined only over tx into blocks, could be extended over other data and knowledge into blocks, such as of hashes over utxo set computed at checkpoints. Could utilize already trusted consensus mechanism (10 years and billions current value) to make skipping genesis validation possible... perhaps even tx stream feeding diffs to database consensus. Alternatively, how do you know you have a valid genesis block and network view? PKI? MITM? Equivalent lols. Read the papers for actual answers.