Well, I can't find it but there was an article recently on here about Apple researching fingernail input capabilities for their touch products. What if this new product is a tablet or macbook touch and instead of a stylus you can use your fingernail to write? I think that this sounds very probable. My theory is that this new product will be a tablet or macbook touch type device. I realize that this is an old rumor but frankly I think that there is a market for this type of thing. Also, like it has been said, the product would be costly to make but because of the prices they'll sell at, Apple will initially see a drop in profit margins. Once they start flying off the shelves then Apple's profits will increase to make up for the loss. This is my theory. I don't really care if you prove me wrong, it's just a theory.
New Apple touch patents show body part sensing, fingernail input
"In what's considered the definitive overview of Apple's attempts to patent its multi-touch interface, a deluge of newly-public filings show Apple considering technology that hasn't yet been used in the iPhone or the Mac -- including sensing the difference between body parts, explaining gestures through activities, and even responding differently to input from fingernails."
About profit margins; lower profit margins but more units sold can equal win.