Whatsapp might stop people to screenshot the private conversation but this is only in the testing stages & it is not unclear whether it will ever be made available for all users.
WaBetaInfo says that in an illogical twist. The authentication blocks those who enabled it from taking screenshots but doesn’t seem to block other users from taking a screenshot of your chats. (Assuming of course these other users didn’t also enable the Authentication feature.)
Read More: The Star Online