They need to sell around 1.5 or 2 iPad minis for every iPad they are replacing. They've already sold 100M iPads. They sold 14M ipads this last quarter, can the market support 22M to 28M iPad minis? I doubt it, but my guess is that a lot of people will go for the iPad mini because people don't want a tablet, they want an iPad, and they don't care which one it is. The fact that it's exactly the same but smaller and cheaper means most people will buy this, in my opinion.