The official Amazon app for Windows Phone is now posting a message stating the app will be retired on July 25, 2016.
The message started appearing today on the app itself, adding that users should now access the retailer's website from now on. Amazon had removed searching for the app in the Windows Store a few weeks ago.
Amazon has not indicated any plans to release a Windows 10 Mobile version of its shopping app. However, it has continued to support its Audible audio books app with new updates, including supporting Windows 10 on PC and Mobile.
Thanks to Dorian for the tip!