I feel like an old man looking at this. The series was never supposed to turn into this big media franchise. It looks like one of those Marvel slides. AC was conceived from the get-go to be a trilogy, and back then everyone could tell because of how the modern day story took a nosedive and turned into absurdity. The quality of the games just reached such lows and no one could fill Ezio's shoes. I remember the AC3 meltdowns, shit was a warzone back then.
Just to illustrate how it started and where it is now. I'm not gonna deny that there were some awesome games here and there that were still fun (Black Flag, Brotherhood) but overall, it's simultaneously one of the biggest and also one of the most mismanaged IPs in all of gaming.