Fin Fang Foom wrote:

I just assumed that Vertigo Crime was going away because DC had made an umbrella decision to pull back on original graphic novels.

You mean graphic novels like that wildly successful Superman: Earth One?
  
Yes, like that one, a success that DC has chosen not to repeat (at least as an OGN):
http://comicsworthreading.com/2010/08/09/dc-backs-away-from-original-graphic-novel-plans/

Again, it's all speculation as to the "why." But from the bits and pieces I have read, I have surmised that the post-Levitz management looked at the OGN track record and decided it just wasn't maximizing profits. In the meantime, they have continued to publish their pre-committed pipeline of OGNs, but that will come to an end at some point soon. And I speculate that it extends to Vertigo, who have had much more success with collection of serialized works, despite the critical acclaim of many of their OGNs.