I'd go for 'notebook' personally. Popular names aren't always the most descriptive or 'correct' ones, just... what most people finish up calling it. And notebook has a current usage which would still be applicable for the device you envisage.
Keep in mind, though, that names tend to simplify through the years. So personally, I'd have one generation calling it a 'notebook' and the younger generation calling it a 'book'. And possibly being castigated by their elders for not knowing what a book REALLY is
