That's what I don't get. I think 1 million copies sold for Shenmue may be asking a bit much. I hope it's not, but gamers these days are a fickle crowd and we have to remember that many of today's gamers never played the first two games. This is why I personally believe it's crucial for Sega to release an HD remaster of the first two games on PS4/PC. Without getting invested in the first two games, I'm not sure people will be willing to invest in the third. Sure, there will be the "story so far" short movies included but that's not really enough for people to get invested I don't think.
First, I agree that it is important for Sega to either release HD remasters of the first two games or give Ys Net the right to do so. As we all know, many did not play either because of them being too young or not having a Dreamcast when they were on the market. Thus, they have to be acclimated to the series properly.
Second, I do not think one million copies getting sold is impossible. It will depend on how well the PS4 version of it is marketed by Sony in the days and weeks after release. It will also depend on how well the community counters those who clearly have an agenda against it for whatever reason. Because KS was the means of obtaining funds, a lot of those with hostility towards that jumped on the Anti-Shenmue bandwagon quickly.
Also, since the late 2000's, there has been this trend amongst those who consider themselves gamers to directly attack Shenmue with nonsense like, "get over it, it's dead," "weeaboo," etc. So, when news broke of Shenmue III coming out, they got mad and attempted to sabotage the KS. Since its success, their anger has tremendously increased, so I believe they will try to now attempt to sabotage sales with false information. That is why the community has to get ready for that now.
Third, it is coming out in both physical and digital forms, so I am not too worried so far.