We're told the EOS 6D Mark II, which isn't expected until early 2016 at the earliest, will move upmarket “slightly” in features and pricing.
We're told again that a big goal with the camera is a smaller size and lighter weight, without sacrificing build quality. The camera will have its own full frame sensor, just like the current camera, along with the addition of NFC. Canon is also working on a “new connectivity feature” that may appear first in the EOS 6D Mark II, but it still in its infancy.
There “won't be anything groundbreaking” in the EOS 6D Mark II, but the goal is to make it a good evolutionary upgrade. Expect bigger things from the EOS 5D Mark IV and EOS-1D X Mark II.
It's far too early to expect any sort of specifications leak, as we're nowhere near that being finalized.