i agree with what you said that bitcoin can coexist with the payment system that people usually use... it can be used as an alternative payment for people who like a decentralized and secure transaction system. although in its use there are several obstacles such as volatility, difficulties for laypeople, etc., but bitcoin offers cheaper, faster, and censorship-free transactions, allowing people to make transactions without problems compared to traditional methods.
As time pushes forward, volatility would be less of an issue, imo.
It would be more capable for bigger transactions mostly, though. And to be a jewel for those willing to invest in it still.