Even though we wish the whole worId would be digital, I don't think crypto currency can make it throughout all rural areas. Crypto transactions needs equipments or machines to process effectively. I dont think it would be suitable to places like wet markets, etc. Still dollar or fiat money is needed.
In the old days, how long before traders fully adopted coins and paper money (from real commodity and precious metals?)?
If ever, it will be the same for transition to crypto. Don't expect it to happen in just a few years.