In our case the copycat sites have "done their time" so to speak after getting slapped with 1-year Google penalties in the past. So they are now apparently viewed by Google as legitimate, even though they came to exist solely off stolen content and link farms a few years ago. So I don't envision them getting filtered off.
It is frustrating how they are now dominating serps when you look at how they got there. But what can Google really do about it? It is beyond their control. They are up against some very smart seo folks.