I think the reality is that they're reacting to uncertainty which may threaten them and both those things are real but for the most part it's really just change and the best way to deal with change is to adapt rather than to fight it.
I think there are valid questions about what happens when the bulk of consumers are people who aren't used to paying for media but in many cases there are alternatives.
There have been a great many times in history where, for instance, movies were going to be killed - the introduction of the TV, the introduction of the video recorder and so on - but they're still going strong. Cinemas got nicer, screens and sound better, the whole thing became more of an experience than watching the movie at home and people kept going to the cinema as a result.
Similarly the music industry has changed it's revenue model to focus on live performances and merchandising rather than album sales. Even if album sales fall significantly they're relatively well placed to cope.
There are valid concerns (I'm not sure what an author does if people stop paying for books for instance) but if the free markets most of these corporations regard so highly mean anything then surely if there is a demand for something (say books) which someone else wants to make (say an author) then the market will, if it's possible, make it happen.
And if it doesn't then maybe we just don't want it that much after all.