I am not sure if it's going to happen. Bitcoin is becoming more and more popular, but I don't think it will be as popular as mainstream services in five and a half year.
It depends on the further developmement of the bitcoin infrastrucutre and the general financial technology.
Yeah, it's really depend on that and depend on the bitcoin user too. If they want motivate other people to use bitcoin, maybe everyone will use bitcoin on 2022.