I’m very eager to migrate over to CFExpress. I have had to replace a couple of XQD cards and they are very expensive these days.
While I’m waiting, I did a bit of research into the history of the XQD format.
The format was jointly developed by Sony, Lexar, and Sandisk as a replacement to the CF (Compact Flash) format.
Sandisk elected not to produce the product and continue development of the CFExpress technology instead.
Lexar and Sony agreed to manufacture the cards. Lexar was owned by Micron but was sold to Longsys 1 1/2 years ago and Sony refused to sign off on the technology transfer for the format so Longsys has been unable to manufacture the XQD format and has also decided to continue with CFExpress development.
ProGrade and Nikon both market XQD cards. Prograde makes their own while Nikons are made for them by Delkin.
CFExpress will use the same card and contacts as XQD so they will interchange, but they have different communication protocols so a firmware update will be needed once CFExpress hits the market.
Nikon bodies using XQD are confirmed upgradeable to CFExpress.
[UPDATE Dec 1st 2020] The Firmware update for Nikon’s D5, D850 and D500 is finally available.