Look, they already have today a 14Mpixel in 1.5 square inches. (Kodak). Multipy that by 70 and you have 1 gigapixel.
So even with today's pixel density, they could get 1 gigapixel with a 108 square inch sensor. This would be approx a 9" X 12" large format camera. Not exactly portable, but imagine the quality of the image if you could get a lens good enuff to take advantage of it! JCO