Earlier quoted context omitted.
You still have no answer for the crypto on/off ramp issue.
I think the idea would be that in a scenario where crypto becomes a currency, there wouldn't need to be an off-ramp (at least immediately, think war/revolution). You would trade the crypto like "real" money.
tldr; either the crypto itself is traded like real money, or a l2 or even centralized unconnected layer is - either way on/off ramps that currently exist (p2p and centralized) continue to exist and thrive.