I'd be inclined to agree. I do not know anyone who doesn't also own a laptop, even the most extreme mobile junkies. They may keep their laptop for longer, and perhaps do not bring their laptop everywhere, which means less coffee spilled on it. But they won't work, refresh their CV, plan the design of their new kitchen or build their budget for the holidays on a mobile or a tablet. Are mobiles and tablet really substitutes for laptops? They probably become obsolete more quickly. But even that is not really the case anymore as the slow down in iPhone sales is showing.