Looks very similar to the concept art seen in the Prometheus : The Art of the Film book.
Well the notion presented in this image makes me think of what ended up happening to the deacon in the Fire and Stone comic series. He literally became the mountain. What if the Engineers are capable of doing the same thing? Do you really think Dark Horse would have had permission to cook up an idea like that on their own?
The idea of the Engineers becoming their own spacecraft or buildings or mountains fits well with their notion of sacrifice. I mean that's what the Engineer did at the beginning of Prometheus to seed the planet. What if the old elephant nosed engineer from Alien was just an engineer who grew to become that juggernaut? It would be a different approach to the one seen in Prometheus, but it could be parallel. The armor that the engineers wear at the end of the film appears to be grown and not worn as we can see no visible seam between suit and body. It could be a modernized version which allows an engineer to interface with a juggernaut ship and then disconnect from it, whereas earlier ships would have required a permanent connection a la Alien Space Jockey.
I just like the notion of engineers sacrificing themselves to become mountains, and buildings, and spaceships. It takes the idea of growing their stuff to the next level. They don't start from scratch. They turn themselves into the objects they need through sacrifice.