Odds of Hanging On
It's not exactly difficult to put a Texas letter in the Texas bag, but it might be difficult to do that 10,000 times a day, 365 days a year—it all depends on your attention span (or lack thereof). If that sounds like something you want to do—and hey, no judgments from us—then you're going to be bagging those letters until the service goes bust.
If you're more the "variety is the spice of life" type, or will eventually feel the desire to get promoted and/or expand your career, then expect to move on after a short stint driving the mail truck.