Here's the thing: Android version updates are a painfully slow affair for every device that isn't a Nexus or Pixel. This has been the reality ever since the operating system's inception, and so far nothing has managed to change the situation. But Google thinks that it can help, at least somewhat, by incorporating a modular base into its OS, starting with the Android O release later this year. Up until this point, here are the steps that have been required for an OS update on a non-Google device to make it into your hands: Quite complicated indeed. But from this point on Android will...
Source: http://www.gsmarena.com/google_announces_project_treble_a_modular_base_for_android_aiming_to_make_updates_faster-news-25004.php