Let’s just say that it’s not at all unexpected that Facebook has shut down M. The extremely limited use cases and geographical coverage of the early demos were just going to be impossible to scale up to any larger audience.
We can see that most of these broader assistants have either folded or pivoted. It seems like a great idea, but this is not the way we are going to get there. Voice assistants are still around but more likely than not they will not branch out into messy offline transactions of the kind that M was delivering. So what is necessary is either for AIs to become smarter or (more likely) for more and more of our lives to take place in a semantically marked-up digital world.