For as long as music has existed, artists have lived from performing. The advent of packaged music (radio, TV, disk, tape or CD) has changed little to this, as the new medium has been more about promoting the artist than making money for the artist, with few exceptions. The ones making money from sales are the record companies, and the appearance on file-sharing is challenging their business model while not affecting the artist's way of living. In fact, the latter appreciate the zero marginal cost promotion. But the record companies want to survive.
Ralf Dewenter, Justus Haucap and Tobias Wenzel study the interaction of record and ticket sales under the assumption that both benefit from each other. Clearly, the impact of file sharing is ambiguous: it may increase record sales if people discover an artist through file-sharing and attend a show. But some potential sales are lost when a very close substitute is available for free. The solution for the record companies to to take over the management of concerts as well. Whether the artists want to go along with that is another question.