If you are beholden to DxO Mark scores as you camera judgment standards, then you know Sony and Nikon have been trouncing Canon in overall “sensor scores” of late. Of course, there is a lot more to a camera than an objective sensor score and many faithful Canon shooters would argue that the results they get from their DSLRs are superior to what a comparable Sony or Nikon model would deliver.
Canon had a successful pro model with the EOS 1D X, which delivered a one-two punch with solid noise performance and a wicked-fast frame rate. However, the dynamic range chart at DxO Mark is dominated by Nikon and Sony cameras, which, of course, rely on Sony sensors.
According to Canon Rumors, the Canon 1D X Mark II is rumored to both increase ISO capabilities with improved low light performance as well as a massive improvement in dynamic range. It would have to push 15+ stops to take the reigns from the Nikon D810 though (that is again if you go by the DxO Mark measurements). Reaching 15 stops would be more than a three-stop bump from where it sits now and where most other Canon full frame DSLRs site.
Of course, the camera and sensor quality will only get better but the DSLR market is shrinking and the mirrorless market is growing. Sony rules the image sensor industry and is only going to continue to build its dominance with the onslaught of automotive image sensor uses (e.g., backup cameras and dash cams), which will have a clear need for improving low light performance. So, if Canon gets ahead on the next generation, I don’t know that it can stay ahead for long.