The developing world is not China any more dumbass. You are like 10 - 15 years behind the times.
You said 6 billion people. Who are they? So you agree then that Chinese can invest because they have a lot of savings and would like to diversify from Renminbi which their government likes to inflate too?
China has already banned Bitcoin for use as a currency.
And you think 1.5 bln. people will just stand and watch in silence their savings in fiat fade away and at least some of those Chinese not try to do anything about it. You're being naive in thinking that if something's banned, nobody will use it. Among other things that can function as store of value they will use crypto currencies too, be sure of it. And it doesn't have to function as currency at merchant level, peer-to-peer level is good enough.