I like your take on things and it reminds me to keep an eye on crypto currencies even though it’s time consuming. I’m not sure about the bell curve. Crypto currencies may be in their infancy but they have been targetted as a threat by the financial system from the beginning. Our FIAT money actually fails one of the key criteria of money — 1.Scarcity (Quantitative Easing). Many crypto currencies don’t fall at that hurdle.
Those in the black market who are entering the crypto shpere are technically already laggards!
Going by your exacmple, assuming the global use of crypto currencies overall by the masses (not just the black market) and the maturity of the technology, I’d say we are overall in the early adopters stage. I think crypto currencies will remain niche. They will not be mainstram without a revolution or a radical change. People will flock to Apple Pay and Android Pay with their FIAT money. Crypto currencies will be an asset class like securities, share bonds etc. for the legal, and remain a black market currncy / laundering mechanism for the illegal activities.
The coubnter argument to my slaim would be I guess that blockchain technology and oter dentralized tech like DAG (Tangle) will be used by corporations but that’s private use and doesn’t interst the most of us. In the FIAT world, it would simply mean more stress for people in their daily lives for working people, possibly more automation.
Tax itself will be the next big thing. As robots enter the fray and more and more regulations come down on them (South Korea just announced plans to tax robots), creative tax avoidance for both machine and human alike will be the norm in the same way wealth preservation and hedge against inflation ar the norm with crypto currencies.