Bill Gates's comment makes sense to me. Apple already achieved the improbable. It seems like a natural time to refocus. They could take steps to make the mobile platforms easier to develop for. They've built an empire, and holding it for the long term requires building relationships and long-term thinking.

The rapid rise of Android strikes me as a significant long-term threat. Apple created a new product category and then allowed a competitor to sweep up the majority of the market, at least in terms of volume. Android is still probably an inferior product, but there are a lot of companies behind it. Android also makes life somewhat easier for developers. I think Apple ought to take this very seriously.