This will have a huge impact on Snapchat, IMO. Instagram Direct allows you to keep a conversation going with close friends, which is much more engaging and fun. Snapchat does not allow for that. One of the reasons that I'm not as prolific on Snapchat is that I just can't know what the hell I'm going to take a picture of next in response to someone's Snapchat. This addresses that issue by allowing just one picture to be the instigator for a conversation. Obviously loyal Snapchat fans will still stay there but I think the less prolific Snapchatters will opt to send a picture this way rather than thru Snapchat.