Well, nothing last forever.
Assassin’s Creed IV: Black Flag‘s director Ashraf Ismail revealed in an interview with Eurogamer that they have always planned on ending the franchise, and they know how the story will end.
“We have multiple development teams, then we have the brand team that sits on top and is filled with writers and designers concerned with the series’ overall arc,” he explained. “So there is an overall arc, and each iteration has its place inside this.”
“We have an idea of where the end is, what the end is. But of course Yves [Guillemot, Ubisoft’s overall boss] announced we are a yearly title, we ship one game a year. So depending on the setting, depending on what fans want, we’ve given ourselves room to fit more in this arc. But there is an end.”
Isamil says that it’s good to have an end day, and annualised franchise. This way, the team can tease and plan the future plot points with great accuracy.
Even though I personally don’t really like the franchise, I have to admit the success and popular of it. It’s good that the franchise is planning on to end, so the story won’t drag on and become boring.