I think one big problem nobody's really addressing is that any artist is now competing with every piece of recorded music every made. Any listener can access pretty much anything whenever they want. You have to be better than, or least different from, what came before.
One could argue that just because, for example, people can hear anything they want from Prince wouldn't preclude finding "the next Prince." But a lot of the signature music of artists still sounds fresh if you haven't already heard it a billion times. Again taking Prince as an example, "Let's Go Crazy" may sound a little dated, but only if you were alive when "the Minneapolis Sound" was fairly common. To anyone else, it has energy and vibe...which is why we listen to music, right?