Why Apple needs more creative iPhone marketing ideas

As smartphone penetration begins to plateau in big markets like the U.S. and China, there's a "rapidly shrinking pool" of potential first-time iPhone purchasers. Manufacturers of low-end devices are focusing on emerging markets like India, but Apple (NASDAQ: AAPL)  is left with two choices: Entice users with mid-range phones to buy iPhones or encourage current iPhone users to upgrade to newer models. And the latter is likely the easier sell.  Commentary