I guess nobody who has the skills to trace hidden services wants to do it. I have been thinking of implementing the trace to entry guards attack, it would take me all of an hour to make a program that would be able to identify any normally configured hidden services entry guards in a few minutes at the most. Getting around entry guards would be more of a challenge for me, since I can not just order their ISP to monitor traffic to and from them. I would give it a shot with a sustained CPU DOS against its entry guards and hope that it selects one of my entry guards while I can maintain the DOS, but that is less sure. One thing though is that I lack any real motivation to do this, I don't particularly want to attack any hidden service and I support Tor. If I knew that I would get $10,000+ for deanonymizing a hidden service, and I didn't have any ideological objection to doing do, I would be a lot more motivated to actually go to the trouble (and spend the money required...at least a few servers particularly if I wanted to try a sustained DOS against several entry guards) to do it.