Well, this could certainly be annoying! To combat overheating sensors, Nikon may place a tiny cooling fan inside upcoming mirrorless cameras, according to a recent patent filing.
Small fans mean high RPMs, which mean high-pitched squealing. Not good. [PetaPixel]
This will be fantastic for extremely long exposures. One of the big problems is sensor noise coming from heat.
As long as the fan doesn't introduce vibrations that is.
peltier version with hot part connected to aluminum camera body would be also nice.