This feature is very welcome, especially after Snapchat's feature copy updates and especially social networking applications that have similar features but don't do it. Facebook has so many options, Twitter only offers public lists, Snapchat chooses users but cannot create friends lists, the closest thing to Google+ is too complicated.
Instagram's solution lies in simplicity and efficiency. The application will make suggestions based on interactivity, or you can create your own lists, no additional items or additional lists. This feature has just been tested but after years of research, it will probably be officially released soon.