20-Year Prospect
Despite the stereotype that customer service jobs will be completely automated or shipped out to cheap labor overseas, employment in this field has actually been showing higher than average growth in recent years (source).
Think about it, the more newfangled technology that comes out, the more confused old-timers there are trying to figure out how to work it. The more online shopping there is, the more people there are trying to return the Alien Ant Farm albums they accidentally bought rather than actual alien ants.
A veritable army of customer service reps are needed, and some of the new jobs are bound to be in the United States.
On the other hand, though, this isn't a job you're likely to want for twenty years. You can attempt to transition into management, but for the most part people usually leave this job to go back to school or transition into a different career. The job isn't going anywhere in the next twenty years, but you probably will.