Components for the revised iPhone (likely to be called the 5S) have been ordered for shipment from late May. Given the lead time for updating the manufacturing process expect to see this model refresh around August or September.
The main changes include a higher mega-pixel camera, 64GB standard ram (128GB option), an even brighter IGZO retina screen and a faster processor – this will simply bring the iPhone up to similar specs to the newer smartphones like the Samsung S4 i.e. NFC, Wi-Fi AC, multi-band “worldwide” LTE etc. See iTWire article on smart phone evolution.
It appears that the 4” screen size will not increase as retooling for a totally new model would be costly and let’s be blunt - the current model is still a top selling handset. Even though many think the iPhone design is “boring” compared to BlackBerry Z10 or Samsung's generic design it is a reasonably timeless ‘classic’ so there is no imperative to change for change sake.
And as nearly 50% of iPhone sales are still of its lower cost, smaller screen 4S, increased screen real estate is not a high priority. The 4S will be phased out and the 5 will become the entry level option. The much maligned Lightning connector stays (I can never fathom why micro USB was not used but thats Apple).
There are scores of other rumours about the new model but so far they are more about wish list items like fingerprint recognition, more case colours (unlikely) and the iWatch extender (unlikely this year - buy a Pebble watch).
There are risks in doing a simple refresh. Will there be enough new features to satisfy the fanboys and create a buying frenzy? ‘…wont be buying this until it brings something new to the table…’ is a typical blog response. I expect iOS version 7 may be the carrot with added functionality, especially in the Siri field. The big issue for Apple is making iOS backward compatible and that could hold back some features until the next “all new” model forces Apple to draw a line in the sand (as Windows 8 Phone had to do).