Your vision will stop getting worse until you reach your early to mid 20s, when your vision will get stabilized. But before your vision is stablilized, you may become more and more nearsighted. However, you won't get blind.
Your vision will stop getting worse eventually. Before your vision stabilizes, you need to wear glasses or contacts to help maintain the eyesight. When it stabilizes, you can have lasik surgery to correct your vision to perfect viison.