Workable Apple TV DVR?

I was reading this article on Roughly Drafted, and I thought of a way to deliver a workable Apple TV DVR: through the USB port. The DVR would be opt-in, so the tuner part would be sold seperately, but it would be a good way to get HD content on the Apple TV. Current Apple TV owners could take advantage of it as well, via a software update. And best of all, Apple is deferring the income from the Apple TV for two years, so that justifies offering a database of listings for at least two years. It would support both satilite and cable by means of a satilite tuner and a cable tuner.
The downside? The USB port is full, so an external Hard Disk could not be plugged in to store all of your HD TV on. However, Apple might also enable remote storage of recordings on an Airport Extreme with a hard disk attached.