You can look up articles over this past year comparing iPad mini to regular iPad sales. After Apple released the iPad mini, regular iPad sales dropped like a rock. iPad mini completely destroyed iPad sales because people could get an iPad for $329 that was portable and easy to carry around. An educated guess would say that Apple conducted research to identify at what price points customers would be likely to purchase a full sized iPad over a mini and found that at $100, customers would be more likely to go ahead and purchase a full size iPad, hence the new price setup for the iPad air and mini. Apple is hoping that customers will consider the decreased weight of the iPad air along with the $100 difference and go ahead and buy a larger iPad air over an iPad mini. What we will see over the next year are balanced sales of both iPad mini retina and iPad Air.