Just a basic intro-to-mopeds book. Have a bit about the history of mopeds, a bit on how to operate one, a bit on safety, your How To Fix tips, some info on the better current models, and maybe a bit on older models and restoring them. I'm sure one of the publishers who prints motorcycle and/or bike books would be interested. As I said, the interest is likely to increase (is already increasing, judging from the price old mo's go for on Ebay) and there's been nothing in print in the US since about 1980.
And books will never be extinct until they develop a cheap internet station with no commercials which you can safely take in the bathtub, to the beach, camping or wherever, and which has a screen that doesn't hurt your eyes after too much staring. :P