It seems, at the beginning of the 90s there were a lot of expectations in regard to DC-nets, considered to be a way better alternative to remailers of the time [1]. At least that's my impression after reading Tim May's FAQ (The Cyphernomicon) [2]. Any progress on this front?
This is a question I always find really interesting. There are still a lot of alternative systems circulating - often in the mid-latency space - which aim to solve design issues of Tor. Someone releases something intended to be a Tor killer every few years, but they rarely last. Tor still remains the only anonymity solution currently operating at global scale without depositing all your trust in e.g. a VPN provider, partly due to network effects (the installed size of the user base is its own protection, so any competitor system is going to perform worse at the outset regardless), the relative lack of tolerance for anything but the lowest possible latency, highest possible usability system for almost all users, and Tor's lasting success in establishing itself culturally as a global brand that can appeal differently to very different user groups. Tor's devs have also been very good at modularising and standardising the tech so it's been great at getting itself incorporated at the ground level of other technologies - and upcoming changes are only going to make that more the case. I do think that there's a good chance for other systems and models to take off that make different design decisions, but they would have a lot of economic, technical, and cultural barriers to circumvent. Not all of them are to do with the theoretical security of the system - for example, DC-net designs were always traditionally quite vulnerable to Denial of Service attacks via collision, and some of the best attacks against anonymity systems can use 'higher security' properties against them. There's a discussion of some of this in Chapters 4, 5, and 6 of the book if it's of interest - also a huge amount written about this by scholars in PETS, WEIS, and other conferences (and blogs, papers, textbooks etc. in cryptospace).
[1]: https://en.wikipedia.org/wiki/Anonymous_remailer
[2]: https://hackmd.io/@jmsjsph/TheCyphernomicon