Well said,
According to your question," if counties like Nigeria and India will allow banks to use cryptocurrenicies"

My opinion here is that cryptocurrency is permissionless, meaning; even if in countries that seems to ban the use of cryptocurrency, it doesn't change anything because the citizens are still making use of it.
As such any bank or country that refuses to make us of cryptocurrency is indirectly doing their economy more harm than good, because bitcoin is the currency of the people, the more the are kicking against it, the more the masses are coming to the knowledge of it and when they discover it advantages over government regulated paper money, they have no option than giving a try and once they're convince about it, then no government can stop them from switching from Fiat to digital currency.

Banks are becoming obsolete on daily basis till when they embrace cryptocurrency, infact we no longer need the banks, seriously because we now discover the safest means of saving our asset, we now have power over our funds, we can now move trillions from on account to the other without any restriction such as daily limit or border, we can now have access to our funds 24/7 without an holiday of any sort.

What do we need the banks for, to come and tell us they're having network issues, to tell us they'll be down during the holidays and you go to the ATM to spend hours only to realize at the end of the day that the ATM cannot temporarily dispense cash, to ask us silly questions while making huge transactions, to tell us to wait for the next 10 working days for our queries to be resolved???

No, we no longer need them to have that full control over our asset any longer, giving us the limit we should withdraw on daily basis.

No, they should not even regulate Cryptocurrency, to avoid unnecessary restrictions.

I rest my case.

Emmanuel Jacobz .
Crypto trader.