Hindsight is always 20/20. What if, under the current trend, smartphone markets continue to shrink, profits fall dramatically in the premium sector, and we decide apple overcommitted to mobile later on, and failed to diversity? It's an entirely possible scenario, to some degree even inevitable.
The vast wave that increasingly _was_, is only good if you can take the cash and catch the next one. Google has search, Microsoft games and business - both software and service businesses. Apple is a hardware company in part - if they are to even tread water, they have to not just win one round, but to win every round, forever. I don't know if I see that in them yet. Profitable - highly - but maybe a one trick pony? Google seems to be doing a better job at diversifying.