a) it doesn't have to be bitcoin (that's why I asked you which other crypto currency will not die);
b) it doesn't have to be recognized and accepted by national banks to circulate among people and perform all functions of money.

All is required is faith by people that it is money and that if a person accepts it, they can easily trade it for something of value (adoption by merchants is taking place). And that is good enough for that to become money, as it performs money functions.