If you're using the Cortana app on your iOS or Android device, then you have until the end of January 2020 to have access to it. Microsoft will be ending support for the app on January 31. Instead, the personal digital assistant will be integrated into Microsoft 365 productivity apps, including Outlook. The Cortana content you made—which include lists and reminders—will no longer be accessible by that date on Cortana mobile and the Microsoft Launcher. Access to these pieces of information will be through Cortana on Windows. If you want access to them on mobile, you will need to download the free Microsoft To Do app.
What isn't clear at the moment is how Surface Headphones owners will be able to configure the settings and update the firmware now. Cortana is how you'll be able to do this.