TL;DR The maximum number of copies that society should pay for a particular title is the number of concurrent readers, watchers, or listeners of that title--this is the theoretical limit of copyright compromise. This may be possible within current copyright law, as long as co-operation can be organized.
We have two opposing forces in the modern copyright battleground. On the one side is copyright maximalists--usually the middlemen--who want to maximize profits and minimize (or at least have little concern for) public good. On the other is copyright minimalists (i.e. the public) who are now part of the distribution system called the internet. Maximalists want to maintain artificial scarcity while minimalists (most people) want to (a) share what they will with friends and (b) not feel guilty for exploiting authors.
According to my understanding of copyright law and the first-sale doctrine, content producers and publishers presently make more money than they theoretically should. They rely on many copies of