More importantly, what would it take to put BTC (or another digital currency) in the hands of hundreds of millions of people around the world to use daily?
For Bitcoin to reach the point where as much as 0.1 % of the world's population are using it, we'd need a reliable, user-friendly infrastructure. We'd need trustworthy exchanges and
"Bitcoin banks". All of this is clearly impossible without some type of regulations, since exchange owners and other BTC service providers currently have every incentive to steal from their customers, as proven by Bitcoin's history.
What do you mean by "Bitcoin Banks"? The whole idea of Bitcoins is, that you don't need a bank.