Cleaning this would be easy if the thief knew what he was doing.
Break the sum into several thousand random size wallets and simaltaneously start a massive hoping trail across various alts and exchanges via a few herds. I would love to see these "heroes" track tens of thousands of smaller wallets converted between dozens of alts, re assembled and mixed again. Estimated loss is 20% of the haul but $180 Million cleaned still isn't too bad.
~BCX~
The problem with cleaning so much money is that it just takes 1 Satoshi to bring things back to him, just 1.
And something further to consider is the laundering itself is going to leave a huge fingerprint moving so much around.
Perhaps a fair analogy is how the NSA can still track people who are using TOR because, in part, of TOR's latency. There is a similar, but much clearer fingerprint the thief is leaving as he moves coins around, cleaning or not. The depths at which Computer Forensics is capable of is mind blowing and then throw some big computers into the equation.
A bigger fear is that these intelligence agencies get their hands on the coins and don't tell us...
You honestly believe he can't swap out every satoshi out? He doesn't have to.
You will never know of you have the right person, ever. You will end up tracking thousands of people, since they all will have some part of that little tag. You can trick yourself into thinking you can find him....you won't.
Regarding washing, what I was saying is that nothing exists right now to wash so many coins thoroughly enough. But even beyond that...
Basically, what I'm saying is, there are so many variables involved (e.g. washing, TOR, VPN, etc.) that he/technology will either slip up somewhere or technology/people will intervene somehow. Might even be a close "friend", lots of money and the police asking questions does that...
Analogously, you hear this talk of side chains with bitcoins, perhaps replacing most alt coins. When the debate on this was going on a year or so ago, I tried to communicate that there would be some type of organic movement that would happen, but it was a bit beyond my event horizon, word wise. I didn't have the words or the direct vision for it. I see the same thing happening with this particular area, this theft, because of the amount involved.