One of my American neighbors here in the Philippines is in his mid-to-late-40's, thinks America is the great evil and will fail any day now, and will be in this situation when he is older. From my understanding, he got a US government student loan for graduate school (chiropractor) and never paid on it. He also had four kids in the USA and left the country (so he must owe child support, two of his children are still minors). He has probably been here for around 8 years.
Before I knew him very well and he told me about the student loans, I told him that this could jeopardize his social security which he laughed off saying that America will be broke anyway. He also just laughed off that he owes this debt. Ironically, his mom is sending money from the great evil America to help support his new family here in the Philippines.
ANYWAY, his American passport is up for renewal in a couple of years. The latest passport renewal form (I just filled it out for myself) requires a social security number, so he will have to provide that (there is actually a financial penalty if you send in the form without it). Will past due child support (California, I think) and unpaid federal student loans disallow him to renew his passport? This would force him to go back to the USA.
He is afraid to ever go back to the USA, stating that he might get arrested at the airport. Also, there is some kind of criminal record there but he served his time, as far as I know. Ironically, he is a model family man here. But this is affecting his family now -- he is refusing to move forward on getting US citizen status for his children here, worried about drawing attention to himself. When it comes to passports, FATCA/FBAR, income taxes, and visa status -- I always warn new expats to not get out of status! Many foolishly ruin their life abroad. I certainly have no sympathy for this guy.