I've been following Bitcoin for five years now, and I've seen this "it's the early Internet, success doesn't happen overnight" attitude that gets more and more false every year.
Bitcoin and the ecosystem around has barely changed since it was released.
And yet it's still going, and with all the turmoil, it hasn't been fundamentally broken yet.
I think in the end, if it remains unbroken (that is, no 50% attacks, etc) bitcoin will become a backing currency for more flexible/faster/easier to use/understand approaches. I think it has a future, but I'm not sure its future is "My mom understands it." It may nonetheless remain useful, and thus, continue to have value, even if itself it never goes "mainstream".
Already it is seeing over the last 2 years a stability in its price that is very comforting. The main criticism is its extreme volatility, but as it is adopted more, as its price goes up, and as more inertia is inserted into the market, it should stabilize even more and cause a positive feedback loop encouraging more adoption. It's doesn't need to be used for day-to-day transactions for it to have value, I think it's already proven that point imho.
The main concern is that this could literally turn around overnight if ever it gets fundamentally hacked/broken. This is always going to be a risk, an uncertainty which might hurt it in the long run. The question is, is this worse than e.g. counterfeit concerns with fiat currency.
Bitcoin has barely changed, but the cryptocurrency ecosystem as a whole has changed massively, and shows no sign of stopping.
But actually the difficulty of understanding it is a big part of what keeps it from going truly mainstream. When the equivalent of AOL comes along and abstracts all that stuff away for people, that's when you'll see Eternal September all over again.