CFexpress is coming. Of that, there is no doubt. It’s the drop-in replacement for XQD and will also replace many of the CFast 2.0 slots on the next generation of cameras. ProGrade Digital was the first to announce support for the new format, back in April last year, but they’ve been holding off on releasing it until hardware comes out that actually supports it.
See the update at the bottom of this article containing a response from ProGrade Digital.