It looks like Samsung continues to ignore the imagining potential of its flagship smartphones, as the latest 64 and 108 MP will first be featured in the top-of-the-line 2020 A-series. According to a recent leak, the entire 2020 A-series will integrate rear triple-cam setups, and the A81 and A91 models will also get ToF sensors.
https://www.notebookcheck.net/Leaked-Samsung-Galaxy-A-2020-models-first-to-include-the-new-108-MP-sensors.430536.0.html