I just saw this picture of the back of my head and I am balding (Photo)?

I am 21 years old, what does this mean for my future?

This is a sign that you will probably continue to bald in the crown.  The drug finasteride, can be applied and maybe reverse this. Try it as you can buy it in the pharmacy,  Keep on it for a year at a minimum to get any benefits. IF it does not solve your problem, see a doctor