yes the ''destiny 2'' etc are refered to in bungie's contract as ''fully fledged expansions'' so basically a new game
2014 = 1 2016 = 2 2018 = 3 2022 = 3 thats three major expansions plus bungie is requires to support and update / bug fix for 3 years after, also after 2016 or 2018 cant remember which bungie can start freely making and doing whatever they want with the franchise