It's always been a one-person job because getting the game out was always the top priority: Maps, skins, animation, sound ofcourse and the unsung heores, code...
AI, based on that, pales in priority, sadly, since it focuses on only those who care for iit - But the beauty of it is, it can be done by one dev, and independent modders like, formerly, WinterHilf (Now dev), and Legion(DCX)
because it doesn't face the same scrutiny as the rest of the game aspects, it can get away with being done by only one person, whicvh implies, being stretched too thin. I sure hope with that consideration, it would allow flexibility for help coming from external sources, like Legion