Well, the Valve modelers and animators would be too busy at the moment, but consider this...
Saxton Hale said:
I look forward to [V] WORKING WITH YOU IN THE FUTURE
Could this mean the original modeler would get to make the model for them?
Stupid speculation aside, this whole thing is pretty scary. The fact that they're posting it on the blog means they've definitely contacted the guy and worked out something, so... whether we like it or not, there's going to be something Guard Dog-related in the game.
EDIT: Well, ok, maybe not guaranteed, it might be a joke that the dog creator guy is playing along on, I just think it's likely.
I think it sounds like a neat idea for a class, even though this brings bad memories from the COD4 campaign. Killing dogs is so horrible. :<