Zero hyperbole required on this one. I can play this game for the next entire hardware generation and I'll still be finding new shit.
This is the first game ever to not have an actual completion time because it can't be completed. There are just constantly new quests and towns and caves to explore. I don't even have any DLC yet but I don't care. I'm going to play the core game, and then enjoy the DLC after which will probably be in about a year because it'll take me that long to play through this game every single day playing for like 2-3 hrs on average.