A patent has been unearthed that shows one of Xiaomi's ideas for solving the problem of the notch. In the drawings contained in the application, Xiaomi has gone with a stick-out notch that stretches beyond the normal display area of the smartphone. The stick-out notch is filled with two cameras facing the front while the rear of the notch is left bare.
https://www.notebookcheck.net/Xiaomi-patent-shows-smartphone-with-ungainly-stick-out-notch.419254.0.html