Before Final Fantasy XV came out, the FF franchise was not as popular as it once was. Square Enix wasn’t sure if it wanted to commit making a 16th game after XV.
As noted by DualShockers and NeoGAF, Hajime Tabata talked about the development for Final Fantasy XV at the Game Developers Conference 2017. The mainline series was in a bit of trouble a few years ago,
Square Enix was not confident that moving away from turn-based combat was a good move and they only set a sales goal of less than 5 million copies for XV.
The scary part is that Tabata said that Square Enix saw the FF franchise as being diminished and in danger. They said if the game didn’t meet sales goals, there might not be a next time.
Tabata wanted to prove his superiors wrong and set his own goal of selling 6 million copies to push the team harder. He confirmed that the game has now sold over 6 million copies and their goal has been met. This means the FF franchise lives on and we are likely to see the 16th main entry sometime in the future.
This is good news for the franchise going forward. It means the series will continue to be a PC/console juggernaut instead of it being watered-down mobile only experiences or something like that.