Marshall said Apple's TV and movie rental business adds about $60 million in revenue per quarter, with another $50 million coming from electronic purchases. By comparison, Netflix reported $550 million in rental revenues for the quarter that ended Sept. 30.

Analysts have traditionally said that Apple's iTunes business -- including sales of music -- is a bit better than break-even. Marshall didn't dispute that, but thought that as Apple's TV and movie rentals increase, it will reap rewards.

"iTunes is all about getting the hook on the customer base, and selling [Apple TV] hardware," Marshall said in an interview today. "But as Apple's rentals scale up going forward, they will generate significant profit. They will start to become more of a profit center for the company."

Marshall believes Apple could see a dramatic revenue boost from rentals in the next five years. "If Apple can grow its rental business similarly to Netflix's historical profile, it's feasible iTunes' annual rental revenue could exceed $1 billion by 2015," he said.

Netflix has quintupled its subscriber base in the last five years, and more than tripled its revenue in the same period.