Most AI assistants can't really hold a conversation. They're fine with I-go-you-go dialogue, but most humans aren't quite so timid -- they know when to interrupt, and when to restart chat when there's an awkward pause. Microsoft wants to fix that. It just upgraded its Xiaolce chatbot AI with "full duplex" conversation that lets it start speaking when it's listening to what you're saying. As it can predict what you're likely to say next, it knows when to interrupt you with important info or say something more when both sides suddenly go quiet. Think of it as that friend who knows when to speak up without being overly rude.
Besides providing a more natural flow to your conversation, it also spares you from using a smart speaker's wake word unless it's actually necessary. Many AI helpers can skip wake words when they want an immediate follow-up ("would you like me to send the message?") but this would keep the conversation humming until you're truly done.
The initial plan is to spread this technology to Microsoft's other chatbots, such as Zo in the US and Rinna in Japan. It's pretty clear that this could be useful for Cortana and just about any other conversational AI, though. Instead of barking orders to a voice assistant and waiting for answers, you could hold two-way discussions that feel more like you're asking real people (albeit ones without much personality) for help.