Permanent loss of nipple sensation after breast reduction surgery. What are the chances of getting sensitivity back?

A change in nipple sensation after a breast reduction is a common complication which will usually subside 4-6 weeks post op. With that being said, some women heal faster than others and vice versa. If this occurrence continues within the next few months, consult your surgeon and carefully discuss your options so that he/she can further advise the next steps to take. 

At
this point in your recovery, it is much too soon to be worried about the
outcome. It takes time for things to heal. There may be sensation changes for up to 2
years. It may be 6 months or more before the shape has reached its final
look. Be patient.

After performing  thousands of breast reduction  surgeries, I can comfortably tell you that because you have loss of sensation at 3 weeks does not mean that you will have complete loss of sensation at 1 year.   I have had permanent loss of sensation in two patients , both of whom were large reductions.  That's a very small percentage, but if you are that person, it can be problematic and even depressing for some patients.   However, at 3 weeks it is entirely too early to know what the result will be at 52 weeks.  Although I am certain that your surgeon discussed the possibility with you, it does not make the "waiting period" any less problematic.  In general , having erectile function of the nipple is usually a good sign that at least some sensation will return.