I don’t think getting rid of bottom navigation is a good idea. Spotify team made a good decision replacing side menu by tab bar. Side menu are never good practice on iOS. It hide major navigation opptions and is less efficent. It makes user to tap twice every time he wants to change the main view. Acessable and good UX patterns are more important than clean interface or pretty looking side menu. Anyway great article, good job with the case study and research.