The Sony Alpha a7 III is expected to be announced sometime in 2017, before the announcement of a7R III and a7S III mirrorless cameras. The price for Sony a7 III will be a little more expensive than currently a7 II.
ilovehatephoto has posted their expect of top 10 features of Sony Alpha a7 III mirrorless camera. You can see a brief detail below:
- The body should remain subsequently identical
- The dial wheel might be switched to a joystick or just be a little bigger
- The screen should remain the same but become a touch screen
- The EVF might feature the same magnification size as the a7R II‘s (0.78x) but without the T* coating.
- The AF system should be about the same as the a7R II or with the new 4D system
- The battery life remains a big question.
- The Sensor resolution might be the same but with better ISO performance and maybe a back-illuminated structure
- New BIONZ image processor, faster, with better noise control and better burst rate (7 i/s? currently at 5 i/s)
- Silent shutter mode? Likely, yes.
- A GPS is not likely to appear, it would consume too much battery life