It would take many more years to be accomplished this.
Indeed I don't think either that it will be used by almost everyone in just 6 years that's not enough time for the bitcoin to grow big enough.
Fiat will remain the biggest currency cause bitcoin is not strong enough to sweep it away.
yeah i agree not really everyone but i think there will be considerable rise in people using bitcoin during that time as more and more are getting aware of bitcoin. also with the convenience it offers, it certain that more people will prefer to use bitcoin. but to be used by almost everyone, i think that's not yet going to happen in 2022