Report claims Apple is considering including the in-display scanner in a 2020 iPhone if testing is successful, but possibly the tech will not be ready until 2021. This lines up with a prediction from noted Apple analyst Ming-Chi Kuo, who expects an iPhone with both Face ID and in-display Touch ID in 2021

Face ID and Touch ID each have their weaknesses. With both systems, users would have the best of both worlds, using the authentication option that is better in a given situation.