First, I don't think there will be any change in the revenues of publishers who were in the business of publishing textbooks, for example. That would be ineffective, as far as I can tell.
There's another regime where maybe collective licensing agencies should not have been given money over the years. In regard to that, I'm referring to the point I made earlier about contests between university administrations and a particular collective licensing agency over what constitutes fair dealing. Those revenues might disappear at that point, but maybe they should never have been expended in the first place.