I'm not of that mind. Days Gone will have trouble finding much of an audience. I'll be surprised if it does half of Horizon's lifetime sales.
That still means 5 million units sold, which I guess is fine. The game has the advantage that it has little competition though. But I find it difficult to predict the sales of this game. If reviews are good I could see it having a +1 million opening and possible over 4,5 million units sold this year. To end up around 6 million tops. If reviews are not good I could also see it fallibg short of 3 million.
Please excuse my (probally) poor grammar