If someone does end up creating a truly anonymous form of currency or payment then you can be damn sure the main people who will benefit are those who want to pay no taxes or those who want to sell services and products that are illegal.
This is the major problem with the Tor network. I ran a node for a while, but the traffic packet sizes and timing all indicated users watching videos rather than doing something useful like advocating for freedom of speech. I've had Tor users hack my web sites and troll on-line meetings for blind people. As far as I can tell, most Tor users seem to be serious ass holes. So, I stopped running my node.
I have a less secure idea for how to do this that would encourage good behavior, but there's little interest on the Tor forum or Freedombox forum. Basically, instead of trying to hide what you do, only hide who you are. If you engage in behavior acceptable to a significant number of your peers, then they could help sponsor your anonymity. If you think on-line gambling should be allowed, you could sponsor some Americans who aren't allowed. If you think China should let their people speak freely without worrying about their Government locking them up, then you could sponsor Chinese political blogging. Normally, Tor "exit nodes" are run by people who believe strongly in freedom, but to protect themselves, they are careful not to look at any of the network traffic from their nodes. If they looked, and saw a child porn ring, they'd legally have to report it. In the modified network, node operators would be encouraged to monitor traffic, report anything illegal in their location to authorities, and report any activity outside a person's claimed need for anonymity to the network, lowering the number of exit nodes willing to carry their traffic. A web-of-trust network could be used to determine how much you should trust someone requesting an exit node.
This scheme would work very well with electronic money, using the original Ripple protocol. I doubt this would meet RMS's requirements, but I think it would be a fantastic step in the right direction. It's less secure because you're network traffic between sessions is associated with the same secret identity, allowing attackers to determine patterns of behavior far more easily. However, the people we all want to support are already doing this. There are famous political bloggers blogging from inside oppressive countries. If you want to use your right to free speech to make a difference, you have to attract a following, and that means having a public identity that people can follow. The only people this system would really hurt are those who wish to act out of the light of any public scrutiny at all.
As Thomas Jefferson said, when you do a thing, imagine the whole world is watching and act accordingly. I think all we need is a little more reality behind the whole world is watching part, and a little more anonymity. You wouldn't need everyone to support you to remain anonymous, but you couldn't PO the whole world either.