For our product (40nm and 45nm), wafer from TSMC is still much higher than from Samsung.
Looking at the RE A5 layout, you'll noticed lots of similarity with A4. I wonder how much of the A5 work is done by Apple internally vs. by Samsung design services; I would guess the standard cell, soft IP and layout is done by Samsung, that makes it more difficult to switch Foundry. Also because Apple/Samsung deal is "Good Chip" based contract, with the current A5 yield, I doubt if Samsung is making any money out of A5. I would consider Global Foundry (Fab 8) to be a more reasonable foundry replacement since the 45nm process characteristics is much similar to Samsung compare to TSMC. Intel will not be the foundry for Apple on 45nm products; maybe for 32nm or 22nm node; But Intel's process is optimized for regularity design and design rule restrictions gonna be a huge problem for low power products. By comparison, the cost from Intel will be around 20-40% more than tsmc or Samsung makes it even less likely to manufacture for Apple.
Samsung is the biggest competitive threat to Apple so it makes sense to move away from Samsung. TSMC is a good cost competitor, but it’s always a question how much technology goes out the back door in Taiwan and China and Apple is coming under increased pressure from no-names. Intel has shown itself to be grossly incompetent at making system level products, so Apple has nothing to fear there. Maybe Intel wins by being incompetent, assuming it really wants to be in the foundry business. 25k wafers a month is a lot of wafers when good times returns to CPU. Intel has no history of saying no to spare resources when CPU calls.
I can see Intel fabs supporting their own relatively high margin products. Being able to compete for more "commodity" offerings is a different ball game. However, Apple did move to Intel CPU's on their computers. Time will tell...
This is very bad news for Samsung. Moreover Samsung's profit has fallen by 30% during this Q1. Needs to be seen how Samsung will compensate for this. On the other hand I am sure Intel will do everything it can to get business from Apple.