I think there is a couple of factors that will keep him out of the NFL from now on. Mostly, he has been injured and suspended for a large portion of the last 4 years. When you add that he has had two extremely big blowups with two different teams, seems to have substance abuse issues(alcohol most likely), and he is 34 years old, it is very likely no team will give him another chance.
You also have to consider that after he pleaded guilty to the DUI and served his suspension this season, he was entered into the NFL Substance abuse program. If he ever gets another chance, he is probably subject to another suspension from what happened.