Apple's market share of the worldwide smartphone market may have slipped, but a new Yankee Group survey (via AllThingsD) shows some promising data points for the company. In a survey of 16,000 U.S. smartphone users, the company found 91 percent of iPhone owners plan to purchase another iPhone when it's time to upgrade, while for Android the number is just 76 percent. And, three quarters of those looking to switch from Android plan to buy an iPhone. Yankee Group believes the incredible customer loyalty that Apple holds will drive market share gains well into the future. The firm predicts that, if these loyalty numbers hold, Apple will surpass Android in U.S. market
