Google has announced that Chrome packaged apps and hosted apps will be phased out of Chrome for Windows, Mac, and Linux.
The Chrome desktop browser has had application support for a while now, and during that time Google found that only 1% of desktop users were actively running Chrome apps, so support will be removed by 2018.
Today, approximately 1% of users on Windows, Mac and Linux actively use Chrome packaged apps, and most hosted apps are already implemented as regular web apps. We will be removing support for packaged and hosted apps from Chrome on Windows, Mac, and Linux over the next two years.
Starting in late 2016, any newly-published apps will only be available for Chrome OS. Existing apps will still be available and developers can still send updates to users. In the second half of 2017, the Chrome Web Store will no longer list Chrome apps on Windows, Mac or Linux and will only show themes and extensions. In early 2018, Chrome for Windows, Mac and Linux will no longer be able to install packaged or hosted Chrome apps.
Your extensions aren't going anywhere, and no changes were announced for Chromebook users — who the majority of actual apps are targeted towards.
Google encourages developers to migrate apps designed for Desktops into web-based apps or progressive web pages using the latest APIs and features available.