Do you think that if ever there becomes more adoption, BTC would be and able to be used for mainstream like a global money? Does the tech work enough that it could handle the global market?
A few years ago, everyone would have said that it was only a matter of days before Bitcoin would be fully integrated at all levels. Now everything looks completely different and the answer to your doubt is negative, Bitcoin will not have a significant place as a means of payment, at least not for ordinary users.
It will become just another trading asset on the stock market, a toy for big players.
With this lack of resistance to spam and high fees as a result, it cannot be considered a reliable solution as a global currency.