6. The failure to get true digital money. Call it what you like, "digital cash" or "ecash" or even one of Hettinga's pet names, but the fact is that for both political and technical reasons we don't have digital cash. This has ripple effects for nearly all of the constructs which depend on digital money: data havens, good remailers, black nets, beacons, and of course for certain sociopolitical implications of untraceable transactions.
Without this basic building block, we are left just with the "privacy" stuff...and the privacy stuff is both fairly boring and at the same time wrapped-up in legal/political baggage about secrecy, hiding things, etc. Boring!
As someone (Bob, perhaps?) says, financial crypto is the only kind of crypto that matters. Other things are interesting and useful, but this is the big one. Let's recap Tim's definition here: the financial crypto we're talking about here is anonymous unlinkable holding of value and untracable anonymous transfer of value. That's what we're talking about. The math and the technology are there, but it hasn't happened, and it isn't any closer to happening now than it was ten years ago. In fact it's even further away from happening. There have been endless discussions of why it hasn't happened, but the bottom line is, various powerful heavily-armed groups (tax collectors and their beneficiaries and many others) would lose literally billions or even trillions of dollars if that happened, so they will put infinite pressure on anyone who tries to do it. If you thought that you were going to lose a billion dollars, what wouldn't you do to stop that, especially if you have the legal power to use deadly force, write laws, and throw people in jail? Therefore, the operators of the scheme need to be anonymous, hidden, or hiding in a cave in Afghanistan (er, maybe that doesn't work anymore). Anyway, there are serious barriers to trusting people who are anonymous with your life savings, and there are serious reasons why such a system may never be stable. So, is there a way to get the system to work? There may be ways, but it's going to be a trick, and until that happens, all the other fun crypto-anarchy stuff won't go anywhere. This list is full of predictions, and here's mine: no anonymous digital cash will exist anytime soon (the next year, or five or ten years). The world goes on the way it always has! If you think back to humans evolving as small tribal groups, certain distributions of behavior were needed: we needed leaders, grunts, artists, craftsmen, risk takers, risk avoiders, freaks, and many other types. We don't live in tribal groups anymore but we still have that distribution of behaviors. Maybe financial crypto doesn't fit into this kind of distribution because it's too great a challenge to too many people. Financial crypto would let people bypass the leader-controler types in many important ways.