Both the 4S and the 4 are competing with the secondary market. My nephew got an iPhone 4 for Christmas and when i asked my brother was it "new" - that is from Apple he laughed. He got it cheaper on eBay. With 2-3 models per year he would probably have gotten the cheapest of this years model, which would in any case have better software support. The market for the mini is now bigger than the iPad 4 by some margin, but the 3 outsold the 2.
A single data point does not make a trend. That's what surveys and sales numbers are for.