Smart cards remain secure no matter how long they are used. The computer inside a smart card can secure information stored inside, limit access only to authorized parties and encrypt (scramble) its communications with other devices.
If the smart card computer fails, the information stored in it remains safe because it can no longer be accessed. Smart cards are designed to work for years. Electronic passports for example, which include a secure contactless smart card inside, are issued for many years, sometimes 10 years or more.