Analysts believe that Apple is working on the next-generation iPhone, dubbed iPhone 6, estimated to release in 2014, which will have a bigger screen display of 4.8-inch.

All previous iterations of Apple smartphones before the iPhone 5 had a display size of 3.5-inch. Apple released the iPhone 5 in 2012 and the handset was the first iPhone to tout a 4-inch display.

Timothy Arcuri, an analyst with Cowen and Company, claims that Apple has finalized much of iPhone 6's design. Arcuri cites Apple's supply chain and suggests that the next-generation iPhone 6 will feature a larger 4.8-inch display.

A recent Wall Street Journal report, on the other hand, cites people familiar with the upcoming iPhone and hints that Apple plans to launch not one but two handsets in 2014. The Wall Street Journal reports that one of the upcoming iPhones will feature a display of 4.5 inch while the other iPhone will sport a display bigger than 5-inch.

Both the models are expected to get a metal casing as found in the iPhone 5s. Apple is also said to be scrapping the plastic body of the iPhone 5c, which was launched in September 2013.

While the iPhone with 4.5-inch display is said to be in development and is also being prepared for mass production, the larger display version is said to be in preliminary development. 

The Wall Street Journal also reported that says that the next-generation iPhone is not expected to sport a curved display despite Galaxy Round and G Flex launched by Samsung and LG generating a lot of buzz for their curved displays.

Apart from the form factor, Apple will definitely tweak the hardware specifications of next generation iPhones; however, no details of the internals are currently known.  

It should not come as a surprise if Apple launches the next iPhone with a bigger screen, as the majority of customers prefer handsets, which have display sizes of over 4-inch, and the demand for the same in the smartphone smarket is growing steadily. 

Apple's arch rival, Samsung Galaxy S4 has a 5-inch display and its Galaxy Note 3 comes with a 5.7-inch display. Currently, other handset manufacturers like Sony, HTC, Nokia and more also offer various smartphones with 5-inch-plus displays.