Just to clarify some points, actually VK Messenger is already the most popular (or one of the most, according to different researches) messenger in Russia. Just to compare: in 2015 users were sending 5 bn messages in VK daily, and 60 bn messages in FB Messenger + Whatsapp. The difference is that FB and Whatsapp are used worldwide, and VK only in Runet (~90M daily users).
Besides that, Odnoklassniki recently introduced its own messenger. So I don’t think that Mail.ru Group is unaware of this worldwide messenger trend.
They also have their own “version” of Instagram — https://snapster.io.
Odnoklassniki recently introduced transactions between users all over the world, so I guess it’s just a matter of time when Mail.ru Group transfer this technology into VK.com.