From the article:
“Ubisoft will also be able, for a fee, to require Microsoft to adapt Activision’s titles to operating systems other than Windows, such as Linux, if it decides to use or license out the cloud streaming rights to Activision’s titles to a cloud gaming service that runs a non-Windows operating system.”
If Ubi is willing to pay a fee, they can force Microsoft to adapt any ActiBlizz games they want to another operating system for cloud gaming purposes.