A device with greater interactivity than the Kindle could service markets that the Kindle cannot.

The market could well be a hardware market. (As opposed to the Kindle which is a driver of demand for content.) I'm interested in being able to display full-page daylight-readable content that I collate and generate, and manipulate it quickly and interactively. I'm certain that many others have similar needs, or will discover such uses once these are available.