A recent report at PetaPixel that seems to have gained traction suggests that the Canon EOS 6D Mark II will be replaced by a full frame mirrorless camera. This report is 100% untrue, the EOS 6D Mark II, which we expect to announced around May/June of 2017, will be a DSLR.
As for a full frame mirrorless camera, we haven't seen any solid evidence of one coming in 2017.
More to come….
Update 12/23/2016: We've updated the language in the post to better reflect the report at PetaPixel.