Is hair transplantation a permanent solution for hair loss?

Yes for grafted hair: The question is a bit tricky in that hair transplantation does not prevent hair follicles that were "programmed" for loss anyway to somehow be "protected" by the grafting process. The transplanted hair follicles are harvested from sites that are resistant to hair loss and when they are grafted to recipient sites they retain their "resistant-to-hair-loss" status despite natural hair loss around it.