The thing with Bitcoin is that it can be ever changing, so yes it could be functional in any circumstance. Becuase if we did hit the point where we REALLY needed to scale because a good amount of the world wanted to use Bitcoin, I think the miners would be able to do it -- I think they'd go for it too. Bitcoin isn't like anything else, we're able to do some crazy things if we need to -- like the lightning network which I really want to succeed.
So yes, I fully do think it can.
I do agree bitcoin can be functional being use as a real currency. In this digital world that we are currently deal with bitcoin can be a great tool as a mode of payment. Yes Bitcoin isn't like anything else, its flexibility and transactionally very convenient. Just a certain studies and public acceptability can make it posible.