I think this movie should absolutely be remade, with the following changes:
The main characters should have to kill a monster, thus fulfilling the promise in the title. This does not happen in the 1965 version.
The whole thing should be transplanted to a remote island in Polynesia. In the old version, there is just no reason to stay in the British mansion on the moors. The characters aren’t stuck, so the stakes aren’t really very high. Whenever the main guy starts saying, “Let’s get out of here,” his British girlfriend comes up with lame excuses to stay.
There should be way more sex. As Octo pointed out, in the 1965 version, there is tons of time where the two main characters are not looking for monsters or talking to anyone else in the house. They must be doing it in one of the rooms of the mansion. We need to see this.
There should be a much higher body count. The monsters have to get free and kill a lot more people, before the college student and his girlfriend turn around and figure out a way to kill the monsters.
Get rid of the British scientist who somehow doesn’t understand that the rock that fell on his property is not dark magic but a radioactive meteorite. I didn’t realize that Britain in 1965 was such an ignorant backwater full of superstitious idiots. For the radioactive rock thing to really be presented as an evil spirit or whatever, you need to move the whole story to a place where the “scientist” is a local tribe leader or a religious freak.