I really think a new Silent Hill could sell at least 2.5 millions consoles with lifetime sales of 5-6 millions. Again, look at RE2 and 3.
You'll have all the horror fans on your side with RE8 and SHR.
It's a SIE first-party so it's gonna sell well anyway, I think even more with it being close to the launch of the console. Just by watching this thread, I'm already seeing a lot of people buying a PS5 just for SHR.
And I don't think any horror IP could do that. It's a legendary horror IP and I think many horror fans who haven't experienced it back then would love to with this new entrance to the series.
Evidently, to achieve this, the game has to be really good and have good ratings, but I'm not worried.