Bitcoin as a high throughput transaction network for buying things like coffee is not a good goal. It should be for much larger transactions, but optimized for decentralization and sound money.
Derivative blockchains can be spun off of Bitcoin, and settled periodically to the "reference" blockchain, which is Bitcoin, through lightning networks or other off chain developments (perhaps some sort of forked derivative pegged chains).
Bitcoin only has value as either a distributed non-centrally controlled international settlement network for countries and large banks [0], and/or as a digital Gold.
Optimizing this value out of bitcoin to achieve transaction throughput destroys the necessity of Bitcoin for existing.
Bitcoin proper should remain resistant to change, distributed, unable to be coopted or controlled by a few organizations, and above all, to have the properties of sound money (so resistant to changes to expand the money supply). If it doesn't have these qualities, it has no reason to be valuable. It cannot be all things to all people, but it can to "one" thing very well.
