No matter how long your single-player AAA game builds steam on the hype train, once it's out, it's out. And then people play it and they're done, and they move on to the next thing.
Unless the game has high replayability, is continuously updated, or has a popular multiplayer component, nobody is going to be talking about it anymore even 1 month later, let alone 3.
Perhaps, several generations ago, when there were long waits between one must-have game and the next, it was different. But there are so many choices now, with more coming every day. There is always something new and shiny coming next week. That's just the reality of gaming today. Or movies. Or TV. Or...basically all entertainment...