I agree that this is some far-off future, but the issue in the near-term is affordance. What can a conversational UI do? The distance from today’s bots to truly useful bots is huge and we will continue to need to leverage interfaces with affordance for discovery for a long time. I’d argue these interfaces are not novice-friendly at all.
Think about how long it takes to become fully integrated into any new relationship. There are norms for the relationship that need establishing over time — this is afforded by casual conversation. Conversational UI’s don’t yet allow that and won’t allow that until they are way closer to sentient. We can try to cover all use cases for norming, but that would be impossible today. Affording knowledge of what the UI is capable of sharing is going to be important for years to come.