CHART OF THE DAY: Can iTunes Save Apple's Margins?

Apple's margins have been compressing, and it has investors worried.

Can iTunes sales, specifically software sales made through iTunes, save the day?

Asymco's Horace Dediu, who made the chart below, speculates:

There is potential for operating margin in Apple Software and App Agency Fees and perhaps some of the Media Transaction Fees (exploded wedges above). Historically, Apple suggested that their App and Media stores ran at break-even but that may no longer be the case. Operating margins from Software may be significant.