The next generation iPhone, which won't be named or showed off until June of next year, won't support 4G. According to sources close to the company, Apple will continue to use the 3G chipset in their next model of the iPhone. This means Apple could focus on building a faster, energy-efficient phone, rather than take criticism for a device that has poor battery life.
However, Apple will be producing a CDMA iPhone by years end that also won't support LTE. Not only that, but sources say that next June when Apple announces next iPhone, those also won't support LTE. This means that Apple won't support the LTE standard until some time in 2012.
As Techcrunch mention, Apple will unveil a 3G GSM and CDMA iPhone next year, which operates on any carrier around the world.