I'm sure this is posted every so often, but it bears repeating. For everyone hoping for a full stop improvement in noise performance in the next model of a camera, it is NEVER going to happen. Today's sensors capture very roughly 50% of the incoming photons. So if a sensor was theoretically perfect, sensors could be one stop better. That's the best they will EVER be, without switching from a bayer color pattern to a foveon-like sensor. ( In that case you could theoretically get over another stop of improvement IF you were still able to maintain the same efficiency. ) So even in another 2000 years with insane technological advances there is no way that cameras could ever be 3 stops better in raw noise performance.
So even if a sensor manufacturer could get close to 100% efficiency now, they would be insane to sell it from a business standpoint. They could release a sensor with 60% efficiency and still be the best, and give customers small improvements for years to come.
We have been spoiled over the past decade - there was a full stop of improvement between the 5D to the 5Diii, but it just can't continue on that pace without breaking the laws of physics.