They're making a sequel, I'm pretty sure it hasn't been released yet. The name's Amnesia: Machine of Pigs. Or was it For Pigs?
Anyhow, I sorta have a thread that asked the same thing, although specifically to Resident Evil, since I believe that the RE franchise is the one most removed from it's origins. I've actually never played Silent Hill, despite wanting to. I just never found time to buy a game from the series, so I can't say anything about that.
Resident Evil has definitely spiraled down in terms of survival horror, and approached a more action oriented game play. And it's sorta disappointing, but personally, I liked RE4-6. Four especially, since that was at least semi scary. The sales for RE6 has been below expectations, so I can't say whether or not Capcom will release a sequel, although they most likely will.
That being said, they announced that the formerly 3DS exclusive Resident Evil: Revelations, will be released to consoles late this year. And that's a brilliant move on Capcom's part. I haven't played it, but I heard it returns to being RE4esque and has some legitimate scares. Maybe they'll catch their fire with it's release, who knows.
As for Dead Space, I actually found that game scary. Not really scary, to the point where I peed my pants, but it has a legitimate scare factor in my opinion. Dead Space 3 scares me, though, with it's introduction of coop play. Look what that did to RE5.
As for Amnesia, it sounds fantastic and really scary. That being said I haven't played it cause eff family computers.