I think you are on to something. But how would your idea compete with T1Visions solution? http://finance.yahoo.com/news/t1visions-showcases-intouch-tm...
Where my approach differs is that it is one screen in the front lobby. It would be used to draw people's attention and provide an informative experience and bypasses the challenge of actual order taking (for now) which makes the software simpler to develop and the hardware requirement much less so the total cost is actually reasonable for smaller/independent restaurants.