Monetization could take place in a number of ways by following available paradigms.
Nothing Is really as it seems: I called an angel, devil had my phone tapped
Amazon has already put in place the necessary specific infrastructure for a store-based monetization solution.
Our tolerance toward interstitial advertising (on both radio and tv as well as the social media) has significantly decreased during the last couple of decades.
It's reasonable to concieve that advertisement interjected in a naturally flowing human-machine conversational dialog could trigger rejections on the user's end and could produce counterproductive side effects.
A mixed regime offers arguably a picture rather close to what we should realistically expect to happen in the very near future.
There is no free beer, food is expensive and wine is served only at the finish line.