Multiple leaks from credible sources has made us believe that the upcoming iPhone will come in two size variants one with 4.8-inch display and another with 5.7-inch display. With displays these big it is highly unlikely for the physical design to complement single hand usage thus we can expect some software changes and UI innovation from Apple in the upcoming iOS to support one hand usage.
There have been talks of new set of sensors which would intelligently recognize single hand usage and change the UI accordingly. If Apple succeeds in making these sensors, then it wont be difficult for the company to make the iOS to have the single hand usage feature.
But again nothing is yet confirmed officially from Apple and thus we recommend you take this bit of information in small proportions. These rumors may or may not turn out to be true. So stay tuned for more.