Rhinoplasty and aging? What determines that the nose will stay “stable” as years go by?

The results of a rhinoplasty will last a lifetime, but the face does age, and the tissue can thin, and the cartilage can grow even.  These are out of the doctor's control.

Rhinoplasty is very stable and after one year the nose will look the same years to come. Facial aging will continue however and few will look in their 70's as they did at 20 or 30. Skin will thicken a bit, the tip will fill out and overall the nose will lengthen somewhat. Rhinoplasty or not, the same changes are likely to occur. If you don't like your present nose rhinoplasty will provide many very good years.