Over the weekend, Windows PC users who opened the app got the following in-app message:
The New York Times will no longer support the NYTimes app for Windows tablet and desktop. You can access a more complete version of The New York Times through your device's browser at our website, nytimes.com
The NYTiimes website includes the same content as the app, plus interactive articles, expanded video features and richer article content.
There's also a FAQ page on the decision to end support for the app for Windows PCs. It shows that the app support actually ended several weeks ago on June 30, but apparently, that news was only sent to the app's users this weekend.
The Windows Phone 8.1 NYTimes app is still available for download in the Windows Store. Ironically, the New York Times Crossword app was updated just a month ago as a universal app for Windows 10 on PC and Mobile.
Thanks to Jaramaine and Brian for the tips!