I don't know about Texas, but in my state of PA. it is very rare for someone to be prosecuted over a hunting accident.
Unless of course there is evidence that it was not an accident.
In Texas people are prosecuted often for involuntary manslaughter for automobile accidents. THIS WAS AN ACCIDENT. But the media will hound Cheney relentlessly as well as the county and state prosecutors. Perhaps a lawyer on this thread might weigh in on this possibility.