Like any new iPhone, demand for the next generation iPhone 5 will likely be high. How high exactly? According to a survey conduced by ChangeWave, it could well be unprecedented, even by Apple's usual, ridiculous, levels.
With 14% of consumers saying they’re Very Likely and 17% Somewhat Likely to buy the “iPhone 5” in the future, advance demand for the next generation iPhone is strikingly higher than for any previous iPhone model.
For example: a similar question on future demand for the iPhone 4S, taken at the time of its October 2011 launch, showed 10% Very Likely and 11.5% Somewhat Likely to purchase the device. Moreover, the iPhone 4S is currently considered the most successful smart phone release in history.
This makes sense, given that the current iPhone 4S was released back in October of 2011 with the same design as the iPhone 4 released in June of 2010. That'll make 27 months between hardware refreshes, which is the longest period in iPhone history. (Original iPhone to iPhone 3G was only 12 months, iPhone 3G to iPhone 4 was 24 months.)
If rumors prove true, and the iPhone 5 has a longer, 4-inch, 16:9 display, it will also mark the first time ever that an iPhone changed screen sizes. Combine that with rumors of LTE 4G networking, the first radio change since the iPhone 3G was released in some 51 months previously in June of 2008, and there's a lot of new technology to demand.
Although Apple does not pre-announce new devices, it's widely expected that the iPhone 5 will be introduced at a special even this fall, alongside the final version of iOS 6, and released shortly thereafter, perhaps in early-mid October like last year.