The latest Nikon patents filed in Japan: in order to prevent camera overheating, one of the patents describes a removable/interchangeable heat storage that will absorb the heat produced by the sensor (Peltier effect). The heat storage can be replaced, similar to to the camera's battery and memory card. This will be especially helpful during long video recordings. One of the related patents described the removable heat storage being located behind the LCD screen which provides a close contact to the sensor through a dedicated heat conductor.
From the patent description (machine translation):
"In a digital camera, a latent heat storage material is arranged near the image sensor, and there are some which suppressed the temperature rise of the image sensor periphery by carrying out accumulation of the heat emitted from the image sensor to a latent heat storage material by a phase change."