With the fiat gateways and wall of coins integration it would seem that already Dash would be better than my local grocery stores...Either way it can be done with crypto or at least soon with DASH!
I think we'd better just accept that it can't.
Life will be easier if we look upon cryptocurrencies as a highly mobile capital asset rather than a slow and cumbersome payments system. Play to your strengths, not your weaknesses.

Blockchains yes but not 2nd tier layers. In btc that would be something similar to the lightning network (censorship prone 3rd parties, semi centralized, not efficient, more fees) and in Dash that would be the masternode network (censorship resistant - protocol level, decentralized, efficient, less fees).
Masternodes meet your criteria as being fast, mobile, flexible and scalable RPS, but you are right that blockchains don't. Masternodes may not have all that functionality right now but it is coming and coming very very soon.