Microsoft announced they are ending support for the Cortana app on Apple iOS and Google Android in UK, Canada, and Australia. The United States still has the app available but I imagine that this will only be for a matter of time. Microsoft killing off Cortana on mobile is a start and they will kill Cortana probably everywhere else moving forward.
Most recently Microsoft added both Amazon Alexa and Google Assistant to Xbox and added Amazon Alexa as on option for voice on Windows 10. A recent support document from Microsoft read as follows
“To make your personal digital assistant as helpful as possible, we’re integrating Cortana into your Microsoft 365 productivity apps. As part of this evolution, on January 31st, 2020, we’re ending support for the Cortana app on Android and iOS in your market. At that point, the Cortana content you created–such as reminders and lists–will no longer function in the Cortana mobile app or Microsoft Launcher, but can still be accessed through Cortana on Windows. Also, Cortana reminders, lists, and tasks are automatically synced to the Microsoft To Do app, which you can download to your phone for free.
After January 31st, 2020, the Cortana mobile app on your phone will no longer be supported and there will be an updated version of Microsoft Launcher with Cortana removed.”
Microsoft has said many times that they only had about 100,000 installs of the Cortana app and Cortana usage peaked none of this is surprising as they have pull Cortana from thermostats and smart speakers recently.