seems like a logical step for me. facebooks messenger is still lagging behind whatsapp in terms of features (ie. it lacks video and audio sharing) and most likely also in users. plus in the past year I've noticed quite a shift from communication on facebook to dedicated whatsapp groups. it's just a much more convenient way to share and chat with close friends and depending on the group you're in it can be kinda addictive. needless to say I would be very disappointed when whatsapp would become part of facebook (especially if it would be linked to my fb profile).