I think what's going to doom Brady and cause a long suspension is his unwillingness to cooperate with the investigators. I don't think the act of deflating the footballs itself is a big deal and he may have gotten suspended a game or two, but nothing major. Now since he was uncooperative and unwilling to hand over information, a lesson will be made of him and it will be a warning to others that when an investigation is taking place that you need to cooperate.
Just imagine if Farmer claimed that he did not send texts to the coaches and the press box and then refused to hand over his phone to investigators. I think him being cooperative lessened his suspension to only 4 games (we thought it would be much worse) and saved us from giving us draft picks. But if Farmer denied and did not cooperate, that suspension would have been much worse and we probably would have lost draft picks.