According to Lee of IHS Global Insight, China's consumers have increased their spending at a fairly predictable pace in recent years, behaving much the same way when the investment side of the economy is growing faster than 10 percent as they are now, with overall growth reported at just under 7 percent in official statistics. Investors have openly questioned whether the official statistics exaggerate the health of China's economy.
The price of an iPhone is still stiff for Chinese consumers who make an average income of about $10,000 per three-person household, Lee said. But the average income of the top 20 percent of the population is about $23,000, making them the primary target of Apple's continued push into China. And consumers in China still have enough savings to keep consuming — though that could change if markets there keep gyrating, he said.
"It depends on the severity and the type of the slowdown," Lee said. A slow, steady decline in growth wouldn't be likely to spook consumers, but "if there's a banking crisis that crushes the economy, all bets are off."
Not all bets. Long-term prospects are bullish enough that Apple isn't planning to pull back on investing heavily in China, Cook said.
"The middle class in China was less than 50 million people in 2010, and by 2020 it's projected to be about half a billion," he said.
But in a possible sign that even Apple is hedging its bet on China, Cook's quickly changed the topic to India — which has a younger population and lower smartphone penetration than China, and where Apple boosted sales 38 percent.
"India is incredibly exciting," Cook said. "It's quickly becoming the fastest-growing BRIC country.''
—By Tim Mullaney, special to CNBC.com