I thought about it again, and maybe if we can apply a good tagging system there would be a chance that those three proposals could live together on the same SE site and would not compete about the same users: Artificial Intelligence & Robotics, Machine Learning, Natural Language Processing and Computational Linguistics (NLP/CL).
If the majority thinks this is a good idea we probably should do the merge before one of the proposals goes to beta and change the name accordingly. In that case I suggest we rename the merged proposal to a name that is a common ground for all three proposals and change the description to: Proposed Q&A site for students, researchers and industry professionals in the fields of Artificial Intelligence, Machine Learning, Computational Linguistics and Robotics to include all communities.
One important point that such a merged site is still attractive for experts from the three more narrow proposals must be that the tagging of the questions is very good (e.g. a ML, NLP/CL or Robotics tag for all questions in the respective area plus the more specific ones so that via favourite/ignored tags the page can be used as if we would have the three different proposals for the people who prefer it that way). So we would have to have some good taxonomists on the site, but I'm optimistic that this is possible.
Please give me your thoughts about merging those three proposals and if nothing crucial stands against it how we can initialize a merge (like it was done etc. for the "Great Outdoors" proposal with Mountaineering, Hiking, Climbing etc. so that the committers are transferred to the unified proposal and the others are deleted).