I don't know anyone whose kept their nipple piercings on for more than a few years. They either get infected, close or the wearer gets bored of them.
From what I understand, they are among the most likely type of piercing to develop infections, but there are probably ways to reduce the risk. Some women I've met say they are fine, that they just didn't want to have them forever. Depends again on the individual, I guess.
Me: bi female in my twenties