I doubt this is true. Facebook wouldnt do such a thing, they dont need cryptocurrency cause they wouldnt consider it safe for their platforms users.
People can already send and receive money with Facebook, there is a feature to send and receive money in the Messenger app. If they want they will do the same for WhatsApp, but it wont be anything to do with cryptocurrencies, these medias are fond of carrying fake news.
I may need to agree with you as OP is not providing any link for source/reference. But, why not a new thing for whatsapp users beyond the features of facebook.
Mark Zuckerberg must have been well aware of cryptos as his 'old friends' Winklevoss twins are icons in crypto world. It is time for facebook corp to react as googlepay and applepay are emerging, hence to stay competitive, they may go for this kind of things.
But, what are impacts it is going to create in crypto space or in bitcoin ecosystem. Nothing negatively, I am sure. Why ? It will be another altcoins but it may get quickly adopted by common people due to the popularity of facebook/whatsapp. But, it may not have value outside whatsapp or at least out side facebook's products. People still need bitcoins.
Moreover I believe, a new crypto from any market giant will help bitcoin to be promoted indirectly as bitcoin is not a purpose specific money whereas all altcoins are.