Can't remember if it was mentioned in the keynote if the X was able to take low light photos - if so then the sensor probably did get an update
[doublepost=1505307131][/doublepost]More digging and I think the cameras are new with new sensors...
Improved Cameras
A larger and faster 12-megapixel sensor. A new colour filter. Deeper pixels. And a new telephoto camera with OIS.
Dual OIS
Both rear cameras have optical image stabilisation and fast lenses for outstanding photos and videos even in low light.
Dual 12-Megapixel Cameras
Can a camera capture more than meets the eye? To find out, we integrated faster cameras with optical image stabilisation, and the advanced machine learning of the A11 Bionic chip. The result is a photography system that sees more, understands more and does more.