I couldn't say for sure whether there's been a change in behaviour. We haven't really extensively studied that.
I should clarify or maybe emphasize the fact that even if someone has Bitcoin in a self-hosted wallet, you can still, through the regular court process, seize that wallet. It can be traced to a person, typically, depending on how they've done it. There are lots of cases where funds held in a wallet, just like a suitcase full of cash, can be seized with the appropriate process.