The document discusses how new communication mediums become marketing channels as they evolve through different stages. It notes that as distribution becomes more expensive, "hacking growth" through finding the right message-medium fit will become more critical. The document suggests some emerging technologies like virtual reality, artificial intelligence, and drones that could become new mediums, if companies can identify matching messages to distribute through them. It concludes by emphasizing the importance of growth hacking to take advantage of new mediums in an era where cheap growth through existing channels is coming to an end.