Displacing might not be the actual word. You could, for example, say that the digital ad market will double in 5 years, and Snapchat will capture all of that ad

Displacing might not be the actual word. You could, for example, say that the digital ad market will double in 5 years, and Snapchat will capture all of that additional revenue, becoming bigger than FB and Google combined. It wouldn't be displacing them per se, they'd still sell the same $ to the same companies. Will that happen? My guess would be on no. I don't think there's room for a 3rd large player in the digital ads world, Twitter tried to be it, but failed. But hey, maybe Snap is able to do it (but I doubt it).