Why would Apple buy Beats when it could just evolve iTunes into a streaming music service? Well, it wants the talent of Jimmy Iovine and Dr. Dre. But according to a source with direct knowledge of iTunes’ executive strategy, by buying and operating an external streaming service like Beats, Apple can coin off a smooth transition without cratering the record business. The record labels and artists depend on the approximately $1 billion iTunes earns them selling downloads each year which could be disrupted if the 800-million account store shifted to subscription streaming. In short, turning iTunes into a streaming-only service is frightening to an industry fast losing cash to streaming upstarts and — by maintaining iTunes as an album/a la carte music sales service while running Beats as a sideline — the company can have it both ways.