Publishers could try to respond by increasing their copyright fees, but that would only create increased incentives for authors to use preprints to bypass the journals. Although library budgets have been increasing, they have been rising at a slower rate than the rest of the academic budgets. However, a more realistic way of looking at the decreasing share of the academic budget going to libraries is that this is another sign of the decreasing importance of traditional publications. After all, there is never enough money for everything, and libraries have to compete with faculty salaries, the football team, the presidential yacht, laboratory equipment, and many other needs. That the libraries have been losing in this competition for funding is another indication that their value is decreasing.
Different areas are likely to be affected at different rates, depending on their practices.
For example, some areas still do not use preprints much, and their transition is likely to be slower. It is impossible to predict exactly how the evolution of publishing will proceed, but it is is becoming increasingly clear that dramatic changes are about to take place.