The rear 3D sensing is said to be powered by time-of-flight technology, which measures the time that it takes for a laser or LED to bounce off of objects in a room, providing an accurate 3D map of the surroundings. The goal is to improve the tablet’s augmented reality features.
The Sellers Research Firm (that’s me) says there’s only a 40% chance of this rumor happening. I think the iPad Pro will get a 3D sensing rear camera, but not before fall of 2020 (or perhaps even 2021). It will debut in the 2020 iPhones first, per my crystal ball.