Might as well delete my version.
Why?
I'm also doing a similar idea to this, I doubt we're going to be the only ones, and it's been done before anyway: See CP_Junction. The map may play pretty badly, but the entire thing is underground and uses displacements instead of any sky. The concept which is setting these ideas apart from Junction is simply the use of vegetation and natural elements, instead of one hundred percent machinery. As soon as I opened up the .VMF file after reading the blog post, I said to myself I'm going to try and use a new abandoned and forgotten underground theme myself, which means more possible work for me, but it might help me achieve a unique look. So it's the same basic idea as Psihomir's take on it, but it has it's own unique twist. Perhaps you could do something similar?
The simple fact that he or she has submitted the thread first, shouldn't mean you feel that you HAVE to delete your work. If you were hoping that no one else was banking on using the same idea, and now that there is other potential competition using the same ideas, pretty much by coincidence and that you simply cannot deal with that fact, then I guess deleting your work is the only option you can take. I still think it's a total waste though and a bit of a silly move to make.
Back to the thread at hand. Looking good so far. As I said earlier, let's hope our own personal ideas will give us enough space to avoid them from looking too similar. Considering aesthetics will be the major area where each submission will differ from other entries.