I was in immigration court today for a detained Master Calendar hearing, and while I was waiting for my client's case to be called, watched as a polite, well-spoken young man was ordered deported (or "removed," in immigration court parlance). He had been convicted of a nonviolent drug crime. The surprising thing was that he had been a green card holder for 19 years! He was ordered to return to a country he could likely barely remember, and where he would have an uncertain future.
Realistically, laws can change. You don't have to fall afoul of the drug laws to get in trouble with immigration... it can be a fight, or a domestic dispute, or something else that could be easily resolved... IF you were a U.S. Citizen. U.S. Citizens can't be deported... so, think about naturalizing as soon as you're eligible!