Mix it all one wants. It remains extremely difficult to avoid others knowing value, otherwise unaccounted for, finding it's way back. That plus a shake down of everyone the person ever knew remains potent, relevant and effective.
I have followed the rough tech developments. None of what I wrote is impacted too much. Obtaining real world value of any significance is where all the weak points are, and where long established means and methods play well.
People are super leaky. Records everywhere, redundant in many cases too.
Like I said, good luck!
There are no longer "entry" and "exit" points because everyone uses it and accepts it. Crypto is a good as cash. Anything you can do with a suitcase full of illicit hundred dollar bills today, you can do with your phone tomorrow.
The trade of "illegal" assets goes on and will continue to go on to the end of time, whether that's marijuana or prostitution services. The spectrum of legality will vary in different parts of the world. Like many contrabands, there won't be enough resources to enforce prohibition of it, the population may not see the point of its illegality (as there is not an obvious social cost), and eventually the tides turn.
That doesn't just happen.
There will be more orders. Who had access to the wallet, etc... Wiretaps, observation, all of it is part of the game now.
In short, investigation will continue, as well all available means and methods applied to better understand who moved the coins and why they were moved.
That is likely to be an expensive, potentially freedom limiting, time.
Being unable to prove it NOW doesn't mean forever being unable to prove things.
Good luck with that game. It's very difficult, time consuming, dangerous, and expensive to play. Your opponents are willing to play hard indefinitely.
Best not benefit from the moved coins in the future.
Both implication and deduction are available legal means too. Remember that part.