I'd be amazed if there isn't an Android companion!
What I'm hoping for more than anything though is that all of the companions have in-depth and cool backstories like in Fallout:New Vegas, which gradually unfold as the story progresses.
I think we've a fair chance of this, with them restricting the number of companions to 12 (as opposed to the shed load we got in Skyrim) is presumably so that they can give them fully fleshed out stories. Otherwise why stop at 12?