WhatsApp seems to be going the YouTube way with its newly submitted beta version for Android 2.19.327. Recently, the company submitted a new update on the Google Play Beta Program for its upcoming 'Dark Theme' feature.
The 'Dark Theme', which by the way is exactly what it sounds like, features such as a Dark default wallpaper. Although it is not yet available to users, WABetaInfo reports that the Theme uses night blue colors and that there will be a System default option to automatically set the theme.
There is also a Dark Splash Screen that is being created for the Theme. This particular update seems to indicate that the screen has been redesigned.