In a perfect world, but we'll probably start seeing ads before the AI answers, or ad banners injected in the middle of a response. If there's a way, they'll find it.
In the free version, that would certainly be how it gets monetized. But a lot of interest is on markets that will pay for the service, such as businesses. I would fully expect this to be a differentiator between Microsoft Co-Pilot on Windows Home vs Windows Professional, or default Co-Pilot vs Office 365 subscription Co-Pilot.