A new research note from analyst Ming-Chi Kuo of KGI Securities was spotted by Macotakara and it details expected changes to Apple's next flagship.
For one thing the iPhone 6S will apparently be 0.2mm thicker than the iPhone 6, possibly in order to accommodate a Force Touch display, which is also mentioned by the research note and has been previously rumoured.
Force Touch would allow the phone to tell the difference between a light tap and a stronger push and respond differently.
The iPhone 6S is also said to be slightly wider and around 0.15mm taller than the iPhone 6. Those are very slight changes if true and they might not be particularly noticeable, but in making the phone thicker it's possible that Apple will be able to avoid having a protruding camera lens this time around, which would make for quite a noticeable difference.
Apparently the colour scheme of the iPhone 6S might be different too, with the current gold colour becoming more of a yellow gold and the space grey option becoming darker.
Kuo also reiterated his expectation that a rose gold model will be introduced and that the new handsets will be made from stronger 7000 Series aluminium and have 12MP cameras, both of which have been rumoured before.
We'd always take analyst predictions with a pinch of salt, but Ming-Chi Kuo has a better track record than many, so the next iPhone may well be stronger, thicker and a different colour.