Nice find mackwheaton..
Apple appears to have seen several instances of supply constraints in displays delaying the release of new products, such as the much rumored iPad Pro. So display production and semiconductor production appear to be the two most important areas where Apple could benefit from becoming more vertically integrated.
Clearly Apple cannot grow this kind of capability organically, so it would have to be by acquisition. With $177 billion in cash, mostly overseas, overseas acquisitions would be the most likely targets. The difficulty is finding the right companies that want to be bought, since Apple doesn't do hostile takeovers.