Analyst Katy Huberty with Morgan Stanley cited an AlphaWise Survey, suggesting that the amount of iPhone users will rise from 30M to 100M by the end of 2011.

Katy Huberty expects Apple to sell at least 42 million iPhones in 2010, significantly growing the active iPhone subscriber base. The “bull case” scenario goes even farther, with 48 million sales this year. The upgrade of Apple’s latest handset will be the key factor for the new purchase. According to the research, 58% of users intend to upgrade their iPhone this year. Thus iPhone enjoys an average upgrade rate of 25 percent.

The analyst predicates that at least 9 million total iPhone upgrades in 2010, increasing to 19 million renewals in 2011. Customers will stick with the iPhone, she said, because redesigned hardware brings new features, software on the App Store creates “stickiness” with consumers, and 57 percent of the U.S. installed base is not fully upgradeable to iOS 4 with multitasking. Besides, AT&T’s new data plans help attract buyers as well.