Apple has varied when the iPhone arrives each year. The original iPhone was previewed in January 2007, but it didn't reach stores until June 2007. The iPhone 3G followed in July 2008, and the iPhone 3GS in June 2009. The last iPhone to debut in June was the iPhone 4, in 2010. Apple then pushed things back a few months, introducing the iPhone 4S in September 2011 and the iPhone 5 in September 2012. A mid-September 2013 debut for the next iPhone 5 was expected.
Looking at the pattern set by Apple gives a general idea of what to expect from the next iPhone. The iPhone 3G and 3GS, for example, used the exact same chassis, as did the iPhone 4 and 4S. There were no significant external differences between the 3G and 3GS, or between the 4 and 4S. Accordingly, the next-gen iPhone (iPhone 5S is the assumed name) should look identical to the iPhone 5 -- the same metallic design, the same 4-inch Retina Display, and the same placement for the buttons and ports. Earlier this year, a report in The Wall Street Journal suggested that the next iPhone will look similar to the current iPhone 5. In other words, there shouldn't be any surprises about the basic feature set of the new device.
[ Apple needs to pick up the pace when it comes to getting new products to market. Read Apple Board 'Concerned' About Innovation Pace. ]
The real questions involve what new things the iPhone 5S might offer to set it apart from the previous-generation device. Many suspect that it may include a fingerprint sensor for security. This is a long-rumored feature, as Apple purchased Authentec, maker of fingerprint sensors, in early 2012. Will the camera be improved? If so, how? What processor will Apple use? Will it have a better/bigger battery?
Along with the iPhone 5S, Apple is also expected to debut a new low-cost iPhone model. In years past, Apple has relied on its older models to serve as less-expensive alternatives. The iPhone 4S, for example, now nearly two years old, is still a strong seller thanks to its lower price point ($99 with a contract). The iPhone 5C (again, the rumored name), is what many believe Apple will introduce alongside the iPhone 5S.
The iPhone 5C will use most of the same internal components of the iPhone 5S, but they will be housed in a plastic or polycarbonate body rather than aluminum. The change in materials is expected to drop the cost of manufacturing the iPhone 5C, which means Apple will be able to sell it for less. How much less is another question.
Apple's lack of a real low-cost device is considered to be a weak point for the company. Apple competitor Samsung has flooded the market with entry-level and mid-range devices offered for free with a new contract at any of the major carriers. Apple's iPhone 4 and 4S are both still for sale, but some reports predict they'll be made unavailable once the iPhone 5C goes on sale.
Apple has not confirmed any of its plans or any of these details. AllThingsD has been on target with its predictions before, so the September 10 iPhone 5S introduction is likely pretty solid. The details to be shared at that event, however, remain up in the air.