The problem is that there's already a promotional agency which takes a cut - the tour promoter! [0]
That industry is slowly converging to a state of brokenness near that of album-selling record labels, as Live Nation (themselves a Clear Channel spinoff) were allowed to merge with Ticketmaster in 2010 to form a unified ticketing, venue booking, and promotion cabal.
That's not a problem. That is just another player. There are tons of people taking a bite of the pie when it comes to actors. Yet they continue to make a living and so do their agents.
That industry is slowly converging to a state of brokenness near that of album-selling record labels, as Live Nation (themselves a Clear Channel spinoff) were allowed to merge with Ticketmaster in 2010 to form a unified ticketing, venue booking, and promotion cabal.
0: http://en.wikipedia.org/wiki/Tour_promoter