Male Pattern Baldness (Androgenic Alopecia) is a progressive condition that is primarily genetically determined. If your immediate family members are a Norwood VI, you stand a high likelihood of the same pattern. However, by combining continuous medical therapy (propecia, minoxidil, low level laser, platelet rich plasma, etc) and surgical transplantation, patients should expect many years (up to decades) of excellent AND stable cosmetic outcomes.
I emphasize this to all patients. Hair transplantation is a permanent solution to hair loss, however, if you transplant the frontal hair line and central core, then stop taking medical therapy, you will continue to loose hair at the temporal tufts/parietal peaks and vertex. Now your permanent solution needs grafting to fill in these receding areas, not because the transplanted hair fell out or the transplant failed.
The age of transplantation is also very important in determining longevity of the result. A 55 year old patient generally has very stable hair loss and will keep his transplant results much longer than a man who requires transplant at age 30 or younger. The younger patient has several factors working against him versus the older patient, namely: increased genetic predisposition, more time for continued loss until stabilization, and requires a longer course of continuous medical therapy to reach the age of comparison (age 55).