Nobody in my household has pirated even one track since the advent of Spotify in our lives. I know it's not the best sample size, and it's only anecdotal, but I suspect that would be the pattern across the board if similar models became adopted for other forms of media.
But their payout is based per stream, not per track, isn't it? At amounts that still exceed that of radio?
"For a 99c sale of a track on iTunes an indie artist gets 70c. At the time you need 140 Spotify streams to make the same 70c." (Source: http://www.spotidj.com/spotifyroyalties.htm)
These figures are hardly comparable with piracy, and for an artist with a reasonable audience, should more than exceed the $.918 average royalty for a song per unit sold that record companies provided in the era of CD sales.