Users who have already installed Chatter Mobile can continue to use the app after Salesforce support ends. But Salesforce will no longer provide assistance in the form of enhancements, investigations, or bug fixes for any issues that your users encounter. After Chatter Mobile is removed from Google Play, it won’t be possible to reinstall the app, nor will users be able to do a new installation of the app on any Android device.
Customers are highly encouraged to migrate to the Salesforce1 downloadable app for Android. We are focused on making Salesforce1 the mobile experience that best serves your needs. Salesforce1 contains the functionality of the Chatter Mobile app, plus a broad range of productivity and CRM features: access to Salesforce objects and records, activity management with tasks, notes, and events, and progress monitoring with dashboards and reports. Plus you can customize Salesforce1 with mobile-optimized Visualforce pages, custom quick actions, and custom or third-party apps.
The Salesforce1 downloadable app for Android currently supports Android phones with Android 4.2 or later. See Requirements for the Salesforce1 Mobile App for more information.