Google already can guess where I park my car and can provide me with relevant traffic data for my commute both to and from work without me having to ask for it.

With highly accurate GPS, and information about the user, you could probably guess what user's home layout looks like, and what they do in each room.

Got a heartbeat monitor on your wearable? Sleep in the same location every night? Haven't had an elevated heart rate in your bedroom for a month? Unmarried (because that's public record)? Time for ads targeted at lonely singles.