The research firm predicted China will reach 20.7 percent of the world’s smartphone market this year, just ahead of the US’s 20.6 percent. While previous research had shown China taking the lead but then falling behind, IDC maintains this latest trend will only continue to snowball. By 2016, China is expected to leverage 20.2 percent of the global smartphone market, while the US will garner 15.3 percent.

“(China’s) smartphone shipments are expected to take a slim lead over the U.S. in 2012 before the gap widens in the coming years,” said Wong Tech Zhung, senior market analyst with IDC’s Asia/Pacific Client Devices team, in a statement. “There will be no turning back this leadership changeover.”

Meanwhile, India and Brazil are expected to be among the top 5 hottest smartphone markets by 2016, with India growing from its current position at seventh to become the third largest market, followed by Brazil, which currently ranks tenth.

The trends are clearly showing developing countries connecting to the Internet via the palm of your hand. The sheer size of these populations combined with a thirst for smarter technology creates a perfect storm of demand that will be close to rivaling the US.

“Demand for smartphones will also grow as urban and enterprise users mature in their handset preferences and usage,” says G. Rajeev, senior market analyst for mobile devices with IDC India. “Consumers are growing accustomed to higher data usage and using handsets for entertainment and other content, instead of just as a communication device.”

Yet costs will continue to be a challenge to these developing markets. The report notes that numerous industry heads at this year’s Mobile Conference in Barcelona stressed the need for affordable smartphones as low as $50 US to propel saturation. In Brazil, smartphones have dropped to below $300 with optional prepaid data plans, propelling the market with room to grow.

“Users in emerging markets seek more than simple voice telephony, and smartphones offer the ideal platform for mobile entertainment, social networking, and business usage as seen in developed markets,” said Ramon Llamas, senior research analyst with IDC.

Remember, there was a decent amount of buzz when T-Mobile sold 1 million iPhones to US subscribers. China’s blowing that out of the water, despite the fact that its 3G network can’t even support the iPhone’s infrastructure, which has been the primary reason China Mobile has given for not selling the iPhone.

Its 15 million iPhone users jailbreaked their phones to use the service, despite the downgrade to 2G due to incompatibility.

China Mobile claims the incompatibility will be remedied following completion of LTE network testing this June, the Next Web reported.

Despite the popularity of jailbroken iPhones, Apple has dropped to fifth place in the Chinese mobile market share, according to a Gartner study.

Apple is set to end its exclusive deal to sell the iPhone with China Unicom, with China Telecom opening sales of the iPhone 4S later this week.

Analysts at Morgan Stanley predict that China Mobile could sell 60 million more iPhones by the end of 2013. With the largest number of subscribers of any teleco in the world at 655 million, the number of China Mobile iPhone fans will likely become exponential, once the country has a network in place that can fully take advantage of the phone’s potential.