He won't go to jail for not paying hospital bills. Medical bills are civil debts. As per the law, you can't be sent to jail for not paying medical bills. You can try find help with medical debt or even try negotiate it.
Nothing will come of it. It would be too costly for them to take him to court and they would end up losing money at that point. Like mentioned, you can't actually face jail time for such thing. Since the debt isn't massive, they will likely just pester him for a few years and it will be dropped after 7. I know it can be scary when they threaten you but they just want their money, that is all.
From what I was told, if it totals over 30 grand, they are likely to take it to court to try and get something out of you but from what I read online, they don't seem to bother with debts unless they are well over 50 grand. I think it really depends on the hospital and the state. I have a friend who owes 60 something thousand from a car accident. She was in the hospital for 8 days without insurance. She has not paid a dime on it and it has been 3 years, nothing have come of it yet.
It really depends. A lot of people don't ever pay them back and while some people may never get hurt by this, others will. It is a risk. I think it is best to just pay them off when you can. Even if it takes a few years.
You can be taken to court for it. I would estimate that you chance of being taken to court for it if it is under 20 grand is like 15% but if it is over 50 grand, you are more than likely going to be taken to court.