We are seeing the rise of intelligent chat systems as the first layer of the user interface. 

There is an excellent article in The Verge on the topic of bots.

An interesting paragraph:

" The fact is, as investor Semil Shah has written, messaging has usurped the browser on mobile devices: it’s where most of our activity takes place. And once you’ve dethroned the browser, which empires will crumble? Could a new e-commerce channel rise to challenge Amazon? Could a bot outdo Google when it comes to understanding what you’re looking for?"

Know one knows for sure if they will be the next UI layer, or a fad, but I would bet on the former.