Today bitcoin is already known worldwide. So we dont need 6 years to be able that all people will be using bitcoin. Were living with advance technology today, and were still uprading every year. It means that even next year bitcoin will be use by almost everyone.
Yeah already a lot of people have adopted it in the current year and in the nest year the adoption will be more and a lot of companies will also start it which will be on offline world and for 2022 I think we will wait for the government steps for it to adopt it.