We're told that the Canon EOS 5D Mark IV will come out with a 30mp sensor. This is the first time we've heard of such a resolution, but it does come from a “retail source”. We're cautious that it could be a number that was rounded up or rounded down, because the most popular megapixel counts have been 24 and 28.
30mp would be a nice number for a lot of people and put some breathing room between the EOS-1D X Mark II and 5D Mark IV. The 6D Mark II would fit nicely around 24mp.
We hope to hear more soon, and please take this one with a heavy pinch of salt.