The R&D and equipment cost for fabrication continues to be closer to exponential growth - which is why so many players have gotten out of the game, why companies with fabs like Samsung and Intel still use TSMC for some parts, and why even Intel is now trying to justify the cost of new processes by becoming a contract fab.

I can certainly see Apple taking a large stake and board position in fabricators, but I can't see them being able to justify the ongoing investment in a closed fab.