Nikon is rumored to announce a new camera with CF Express memory card (or cards) in Q2 of this year. It is not clear whether the new camera will be mirrorless or DSLR (my bet is for a new DSLR camera). This information is coming from one of the companies that make CF Express memory cards and are currently working with Nikon.
The new CF Express firmware update for the Nikon Z cameras is also expected to be released in the second quarter of 2019.
So far ProGrade, Delkin, and Apacer have announced their plans for CF Express memory cards. Lexar has been struggling to bring their XQD cards to market and I have not seen any official statements from SanDisk about CF Express.