The App Launcher is also being redesigned for the Winter ‘17 launch. When users start an App it will present the app’s name, logo, and description on an app tile. The description used to create the app (custom or connected) will be the default text within the app tile. If your organization created custom apps for Salesforce Classic, they will automatically work in this new Winter'17 version.
For better or worse these changes are permanent and organizations using the Lightning Experience will not be able to opt out.
For Winter ‘17 only the Lightning Experience is getting the new navigation user interface.
Salesforce got a lot of feedback from users and partners saying that the current Lightning experience could be optimized to favor productivity. Therefore, changes are being made to save users time and facilitate access to items they need the most.