I think Cryptocurrencies will change the world, to what extent I am not sure however I am confident in the underlying premise of the blockchain. With that being said I think there is one thing being overrated by advocates for blockchain/cryptocurrency and that is the importance of: de-centralization and privacy to older generations.
Most younger generations value their privacy and are quite anti-corporate. Older generations simply aren't too concerned about privacy and corporations with significant power. The whole argument for privacy went out the window with the release of the NSA files by Snowden. For the significance of the files there was very little outcry from older generations with some even calling him a traitor and coward. If older generations seem to think what the NSA has been doing isn't a problem I find it hard to believe they care about their personal data and power of the likes of Google, Facebook and Amazon.
We forget the older generations have only really just started accessing the internet and new technology on the same scale as younger generations have been for most of their lives. To them the internet and companies like Facebook, Amazon and Netflix are amazing. After all, in their younger years all they had was television, radio and newspapers that were monopolised by a few companies - which is part of the problem as they have never really been able to see the reality other than what was presented to them by mainstream media.
The key question is to what extent do older generations care about de-centalization and privacy over convenience? That is essentially what is the main selling point of blockchain. I would suggest most of the older generation doesn't care at all, as long as they are experiencing convenience and utility from newer technology.
If you remove the allure of de-centralization from cryptocurrency it loses a significant amount appeal in the short-term. While older generations may not care, younger generations certainly do and as long as governments around the world continue to let down the people, the adoption and interest of cryptocurrency will increase. I am inclined to believe that investors in cryptocurrency are probably over-estimating the importance of de-centralization and privacy to the largest demographic of investors, as a consequence the time frame for true mainstream adoption is likely to be later than we currently anticipate.