15" macbooks could never really cannibalize the sales of MBP's. Pros that require a computer with an express slot, higher RAM support and a dedicated GPU that can support larger cinema displays will still go for the pro. When I purchase my next Mac laptop, these are the things I'll need, the size of the on-board display is not as big a deal to me since I find the size of the MB's 13" pretty decent. I live with mine just fine, but I want to get a pro machine as an upgrade, not the same consumer laptop with a larger screen.