Apple has used an alternating "S" naming formula to mark years where the iPhone does not receive a major redesign since the debut of the iPhone 3GS in 2009. Releases have been as follows:
2007 - iPhone
2008 - iPhone 3G
2009 - iPhone 3GS
2010 - iPhone 4 (new design)
2011 - iPhone 4s
2012 - iPhone 5 (new design)
2013 - iPhone 5s
2014 - iPhone 6 and iPhone 6 Plus (new design)
2015 - iPhone 6s and iPhone 6s Plus
The next-generation iPhone is expected to be called the iPhone 7. 2015 marked an "S" iPhone upgrade year that introduced new features such as an improved camera and a better processor, but 2016 will bring an even-year upgrade that will likely include an all-new iPhone design.
We are too far away from the iPhone 7 launch to know what the new device will look like, but we can speculate that Apple will continue on its path of introducing more powerful, efficient devices that grow thinner with each design iteration. The iPhone 7 and iPhone 7 Plus are expected to include next-generation A10 processors produced by TSMC.
It's likely Apple will continue releasing two versions of each iPhone, so we may see an Apple iPhone 7 and an Apple iPhone 7 Plus in 2016. Apple may stick to 4.7- and 5.5-inches, or take the opportunity to further refine screen sizes, shifting the dimensions somewhat to match the company's design vision for the updated phones. The iPhone 7 and 7 Plus are expected to feature the same 3D Touch feature introduced with the iPhone 6s.
Though the iPhone 7 isn't expected to launch until September of 2016, we're already hearing some rumors about the device. One rumor out of the Asian supply chain has said Apple will switch to glass-on-glass touch panels for the iPhone 7, potentially allowing for an edge-to-edge display, but a second, more reliable rumor from KGI Securities analyst Ming-Chi Kuo, has disagreed with that point, suggesting Apple will stick with in-cell panels.
The continued use of in-cell panels for the iPhone 7 will allow Apple to make the device even thinner, approaching the thinness of the iPod touch at a point between 6.0mm and 6.5mm. Apple's current iPod touch measures in at 6.1mm, compared to 6.9mm for the iPhone 6 and 7.1mm for the iPhone 6 Plus. Like the iPhone 6s and the iPhone 6s Plus, the iPhone 7 will also use 3D Touch technology.
Apple may also be able to decrease the thickness of the iPhone 7 by up to 1mm by eliminating the headphone jack and instead adopting an all-in-one Lightning connector. According to Japanese site Mac Otakara, Apple will nix the headphone jack and instead introduce a Lightning port that will support both charging and music playback with Lightning-equipped headphones.
Apple may release EarPods with a Lightning connector alongside the new iPhone, and it's likely the company will produce adapters to allow existing headphones to plug into the device should it decide to eliminate the headphone jack.
Apple is unlikely to adopt AMOLED displays for the foreseeable future, according to Ming-Chi Kuo. This means the iPhone 7 will continue to use existing TFT-LCD display technology.
Apple has also reportedly ordered LCD display drivers from touchscreen supplier Synaptics for its next-generation iPhones, suggesting its work on display driver integration (TTDI) chips may not be on schedule for inclusion in the iPhone 7. TDI chips pave the way towards an integrated display and Touch ID module, potentially doing away with the Home button, but it sounds like the iPhone 7 and the iPhone 7 Plus will continue to feature a Home button.
Early rumors about the iPhone 7 suggest the next-generation device may have a strengthened, waterproof frame that ditches Apple's traditional aluminum casing for "new compound materials" that may also do away with prominent antenna bands on the back of the device. The new body may be able to withstand both dust and water, making it better able to hold up when exposed to the elements.
According to another prediction from KGI Securities analyst Ming-Chi Kuo, the iPhone 7 and the iPhone 7 Plus may have differing amounts of RAM. The smaller 4.7-inch iPhone 7 may ship with 2GB of RAM, while the larger 5.5-inch iPhone 7 may ship with 3GB RAM. Apple has included different features in the two devices in the past, with the iPhone 6s and the iPhone 6s Plus offering different camera technology. The iPhone 6s Plus has Optical Image Stabilization for photo and video while the iPhone 6s does not.
Storage space may also be a differentiating factor between the iPhone 7 and the iPhone 7 Plus. According to an unconfirmed rumor, the larger iPhone 7 Plus could include a high-end 256GB storage option that would not be available with the iPhone 7. 256GB is a capacity that is not offered in any of Apple's current iOS devices, so it is questionable as to whether Apple would introduce such a high-capacity iPhone. The rumor did not include a mention of other storage tiers that would be available for the two devices.
The current iPhone 6s and iPhone 6s Plus have different battery capacities, with the larger iPhone 6s Plus offering a much longer battery life. The same is likely to be true of the iPhone 7 and iPhone 7 Plus, as the larger device will be able to hold a bigger battery. One questionable rumor suggests the iPhone 7 Plus could potentially include a 3,100 mAh battery, which would be 12.7 percent larger than the 2,750 mAh battery in the iPhone 6s Plus. Given that the iPhone 7 and 7 Plus are rumored to be thinner than the iPhone 6s and 6s Plus, it is not clear if Apple will actually increase battery size.
A sketchy rumor out of the Asian supply chain has suggested Apple is experimenting with at least five different "iPhone 7" models with hardware features like a USB Type-C connector, wireless charging, multi-Force Touch, dual camera configurations, and Touch ID embedded in the display.
While these could indeed be features Apple is exploring for future iPhones, the technology planned for the iPhone 7 is likely long established and is not rumored to incorporate these capabilities at this time.
We still have a long wait until the launch of the Apple iPhone 7, but the iPhone 6s and 6s Plus launched in September of 2015. Check out our full roundup on those devices for more information on Apple's latest iPhones.
Beyond the iPhone 7
The iPhone 7 hasn't launched yet, but we're already hearing rumors about iPhones that will be released in 2018 and beyond. Apple is said to be working on OLED displays for future versions of the iPhone, at a secret lab it's opened in Taiwan. Apple is also developing more advanced versions of liquid crystal displays, working on a technology called Micro-LED.
Apple is also pursuing an OLED partnership with LG Display and Samsung, and is said to be close to a deal. Under the terms of the deal, LG Display and Samsung would both provide Apple with OLED displays for future devices.
Both OLED and Micro-LED technologies eliminate the need for the backlighting that's used in traditional LCDs, which would potentially allow Apple to cut down on the size of its iOS devices. Micro-LED suffers from low yields and OLED has a shorter life span, so they are both technologies that are not quite ready for near-future iPhone upgrades.
Apple is also rumored to be developing a next-generation version of 3D Touch, which would scale up for use in larger devices like the iPad Pro. Other benefits are not yet known.