I'm not a western or noir fan...
Me neither.
Just going in the opposite direction.
There may be hope for me yet, but, if they do it, or if someone else does it, then I presume I should not, is that it?
H3ll, no!
MAKE YOUR VERSION!
http://en.wikipedia.org/wiki/Heart_of_Darkness
The book's in the public domain.
Adapt away.
Look, the odds are pretty thin of you having very similar enough plot & story as someone else considering the different resources the two of you are sure to be enough to ensure "creative diversity" - even if given the same script to follow as an out line.
For God's sakes, look at the variety of submissions to any given 48hr film festival or similar challenge.
Furthermore, EVERYONE's gonna notice a difference between a homegrown film and a studio produced product.
Just... quit even trying to compete.
BUT... !
BUT... !
BUT... ! There are actually a lot of people that seek homegrown indie films and shun Hwood films, so... gopherit!
Just because a lot of other folks couldn't make a flying machine or sail around the world doesn't mean no one can.
Likewise, just because someone else can't find that magic opportunity to adapt 'HoD' doesn't mean everyone should just quit.