Again, these are all just rumors, but it could make sense.
“Cthulhu is a fictional monster created by horror author H. P. Lovecraft, and is one of Lovecraft’s Great Old Ones. It is often cited for the extreme descriptions given of its appearance, size, and the abject terror that it invokes.”
So this is what people currently think the movie could be about, and it sounds like it could be pretty cool if it is done right, but we’ll just have to see. Click the link below for the full wikipedia entry about the Cthulhu.