From reliable source which has never been wrong!
http://digicame-info.com/2015/01/eos-5ds-eos-5ds-r.html
In Japanese, Google English translation here.
So, the 645Z is not unique again, and the upcoming 5Ds should be much cheaper, at half of the 645Z price very probably, but yet provides the same pixel count, and is a much faster camera of which the system has far more lens choices and much better portability.