Yeah, after you have motion down, you would just need to be able to detect a heat signature and shoot at it. I doubt that's very difficult compared to what they've already done.
There are already robots for that. Not so fancy, but they somewhat work.
I wasn't speaking about "robot world domination". That implies intelligent machines and this is not. But it looks like this one is pretty efficient in recognizing obstacles, and shapes. Once they can recognize targets, humans just need to deploy them and they will be much more efficient, without the need of human pilots. And they can come in different sizes and shapes.
I find it quite scary, and the DARPA logo at the end of the movie does not help.