I think the biggest issue with AI assistants is simply that people aren't comfortable talking to them in public. It just doesn't feel right and I've never seen anyone do it elegantly. Actually I've probably never once seen anyone use an AI assistant on their phone in public. Which is why I only ever use it when alone, if ever. It's useful for asking the time when you're half asleep and your phone is across the room, or for setting up quick reminders. But anything else is just unnecessarily complicated and prone to failure.