I enjoy them but the last true AC was Syndicate. It's turned into RPG semi fantasy. I want it to go back to the roots. The RPG elements can make sense but as of now it's just used for grinding and forcing you to play a certain way. Games are still fun but I'm afraid with something like a service model, it'll turn more into RPG and less lore. They already did with Valhalla. It'll sell better but be less AC like.
Again it's still fun. But as you said it'll be for what sells. And that's not what I'm interested in. I want a full $60 worth of 100 hour gameplay and they are definitely not going to have enough time in a service model for that. Probably be expansion/large DLC releases every handful of months. Doesn't sound as appealing.
I think if it was a substitute for in-between the large single game releases that could work. Have the main game be the massive historical moments and then work on the next one, in-between can be expansions and DLC that can be full of ideas and or other time frames.
