To believe that the most fundamental social human issues can be solved by technology is a bit of an utopia imho. Greed, lust for power, envy, etc. Those are part of human nature, i don't think they will disappear thanks to some elaborated algorithm. Unless you want algorithms to take control of social interactions (which is another kind of shite society).
BTC, LTC are traceable, so you can still track down owner (although it may be extremely difficult in some cases).
But with technologies like zero-knowledge proof in ZCash, you have untraceable money.
So at some point, when cryptocurrencies hit mainstream, you may see the situation when people start exchange goods and services directly in ZCash or Monero. I just don't see how government can shutdown this.
I don't see how governments can crackdown cryptocurrencies completely. So in long term, impact of cryptocurrencies on global economy is inevitable.
The blockchain is a human construct, entirely dependent on human inputs, outputs, and interpretation to have any meaning at all. As long as that's the case (and if it isn't, then it's not useful to society), it has the exact same weaknesses.
It's entirely possible if not probable given enough time and enough tries at it, someone is going to find a really useful application for it. But it's hard to take statements like "catalyst for social change" seriously when its sole contribution to this point has been a new form of gambling. There's a big disconnect between what the technology is supposed to do and what's actually happening.
Although I still think it's going to be a very long way off if western government's can't work out how to make unauthorized use of crypto illegal.