There were rumors about iPhone 5s having 128 GB capacity but it never became a reality. This aspiration shifted to iPad mini with Retina Display, and one iPad Air model. The powerful and higher memory suits the devices with larger screen; rather 4" iPhone 5s display.
The current year seems to be the time for larger iPhone screens. The rumors are pointing out that such large memories will be reserved for the upcoming handsets like Apple 5.5 inches phablets. It is further guest that 128 GB of storage will be suitable for Cupertino's upcoming handsets. This is further confirmed by the news and rumors about the supply chain sources that confirmed it will be used in the 5.5" Apple phablet only, while the 4.7-inch iPhone 6 will remain with 64 GB at the most. However this is another option that the 4.7" iPhone 6 will be further reduced to only 32 GB and there is no chance of 16 GB; reality is yet awaited.
According to the recent research the 5.5" phablet will be the one that will uses an optical image stabilization option for its camera, but the 4.7" iPhone 6 does not have the option available in camera. If the latest news about the 128 GB memory is restricted to the phablet, visibly Apple is planning to distinguish its big screens much further than simply producing a larger display diagonal.