I think the “beer-in-a-stadium” case is great to understand how Lean Bot-based UX will be.

Also, I see a great potential to test new business models in a Lean Startup way using Bots to check the main KPIs of user conversion / retention at a very low price, especially if you have the same shared and trusted payment services that Apple & Google already offer on their App Store. We’ll see on April 12th at F8 if Facebook moves first in these uncharted teritories.