The problem however is that a nation's currency is arguably the primary source of it's sovereignty. Whomever controls the currency primarily used in a nation, controls the nation. So it's safe to say that no nation is going to let bitcoin or any other currency take hold for widespread commercial use in lieu of it's sovereign currency - that's a hallmark of a failed state.
In fact that's why when regulators declared bitcoin as a commodity it was such a big deal. The US doesn't really care because we haven't had commodity money since the 1970s, but the idea that if enough people decided that they wanted commodity money, they would arguably have a medium with which to do it with that wasn't tied to any state.
So as with every product, unless a massive number of people decide to stop using their home currency and start using bitcoin, then bitcoin will "fail."
Whether it pivots to some kind of credit system or not is largely immaterial because of the potential it had.
It's like if we created Artificial General Intelligence and it decided to just write movie reviews forever.