"What will be the role of government then; since there would be no taxes"

Who cares if the government gets no taxes? What would an average person lose?

"Some people and even countries depend entirely on cash."

Simply because they don't realize that Bitcoin is here, they think they have no option.

"What about the unequal distribution of Bitcoins among humans?"

It's the fiat, which has unequal distribution. Imagine the gap between the west and the global south. Bitcoin fixes this.

"Everyone (i mean every single human) would need to have a digital device to store, spend and earn bitcoins on."

That shouldn't be a concern. This is digital era. In fact, we already have Boltcards, Machankura USSD, etc. For instance, people in the poorest countries in Africa are using Bitcoin easily with Machankura.