Of late, Google seems to be hard at work in trying to give their entire system UI a dark theme. Not only does it make the app look better, but on OLED displays, it also helps save some battery. Now, it seems that Whatsapp will follow suit and could soon implement an app wide dark mode.
As per findings by WhatsApp tracker, WABetaInfo it has been reported that WhatsApp beta 2.19.82 includes Dark Mode related code. This code is still being worked upon meaning that it is not available for users yet. WhatsApp had reorganized the Settings layout in a previous beta, and it can be assumed that was done to implement Dark Mode properly as the leaked screenshots only show the settings page in a dark theme.
Since the only the settings menu of the app has been revamped, it leads us to believe that the change is still in very early stages of development. The end user will not spend a lot of time in the settings menu and therefore, the chat screen will have to be carefully restructured to make way for the design change.
Though you can still go for a similar look by using a dark wallpaper, it won't be the same thing. Another interesting bit from the report is that WhatsApp Dark Mode for Android won't be as OLED friendly as the iOS version. In other words, Dark Mode on Android will not use a black background.
The last Whatsapp update added a feature with references to a new 'frequently forwarded' label. With this, they aim to tackle the spread of fake news and curb the issue.