It will have to come. Football results are now so important and there can be so much hanging on a bad decision that Football needs the video judge.
For example. When Andy Carroll hit the Liverpool goalie in the face and knocked the ball out of his hand. The linesman saw it and waved for a penalty, this was overruled after a while by the ref. All this while it was being repeated on the big screens at the ground. The players all telling the ref to look. So, just a quick look could have told him his lineman was right.