The strategy certainly makes sense as long as as Jobs continues to win territory in his war against DRM, and the subscription music services fail to lure a critical mass of consumers.
More than 2.5 billion songs have now been purchased from iTunes and they control 85% or so of the download music market. DRM free songs on iTunes cost 30 cents more, almost certainly creating greater margin for Apple per song.
The subscription music services are highly competitive, leaving little profit for the providers. As long as Apple can keep selling tracks for a dollar or more per track, they’ll resist entering this market.