We are very close to the WWDC 2017 that will show iOS 11 to the public.
iOS 10 brought many new features in WhatsApp and developers will continue to add new features compatible with iOS 10+: it will be the turn of Rich Notifications.
There won’t be an option to configure them. Rich notifications will show a preview of received photos if your autodownload settings are enabled.
You can also view, like happens for other applications that support Rich Notifications, the full picture in the notification, expanding it and sending your reply.
Note that this feature is disabled by default (learn here what is a hidden feature) and it will be enabled for all WhatsApp users in next stable updates when WhatsApp developers will be sure that the feature is finally bug free and it is ready to be used.