FFXVSo FFVIIR* is going to have 100% growth over FFXV while only releasing on a single plateforme this time?
*2/3rd of the game not included, check with your local Walmart for more information
November 29, 2016 - PS4/XB1 launch, 5 million shipped
January 10, 2017 - 6 million shipped
February 23, 2018 - "about 7 million shipped"
March 6, 2018 - PC launch
June 7, 2018 - 7.7 million shipped
September 7, 2018 - 8.1 million shipped
November 8, 2018 - 8.4 million shipped
15 million would not be anywhere near 100% growth over what FFXV's LT sales will be. FFVII has so much more going for it than XV (and by the way, it won't be exclusive to PS4).
The episodic thing will have the same impact on FFVII sales as the Dexit has had on Pokémon Sword/Shield sales. None.