Hair transplant after 5 years? Stages?

What you point out is called a Master PlanIt involves obtaining a diagnosis and a discussion with your doctor regarding possible future hair loss and the overall treatment plan.  Read more about it on the link provided.

Your concerns are justified and very sensible. This is why a very important part of planning your hair restoration journey is to choose your surgeon wisely. A good hair transplant surgeon will have years of experience and will know the pitfalls associated operating on a patient with progressive hair loss. During your consultation a good hair transplant surgeon will try to judge the risk of advanced hair loss based on family history, age of onset, speed of progression etc and explain to you what is an appropriate transplant design taking these factors into account.

One of the most important aspects of your consultation for hair restoration surgery is the surgeon's ability to evaluate your hair loss now and where it will be in the future. What happens in hair restoration surgery is that hair that is resistant to the hormones which cause male/female pattern hair loss is transplanted into the area where men/women lose their hair. The hair continues to grow there as if it is still "living" on the back of your head. The problem is what if hair loss continues and you lose some of the remaining hairs in the front of your scalp because of progression of hair loss?Because of this, I generally recommend considering medical hair restoration options in addition to surgery. After all if you are able to hold onto the hair near my transplants (or grow more hair near my transplants) the final result will be better for you and for me. So best option is to consider Rogaine and/or Propecia in addition to surgery. Also, I don't generally recommend hair restoration surgery for very young patients (e.g. under 28 usually) or patients with very rapidly progressive hair loss. Best option usually is to consider medical hair restoration options in those patients and let things stabilize because again your hair restoration surgeon has to create a result that will look good now and also look good in 20 (or more) years. Good luck.

Genetic hair loss is a progressive process and if you are in your early 20s, what you decribed is almost a certainty unless you are taking the drug finasteride daily which will slow down or stop the hair loss you may be destined to have.  Taking the drug finasteride before and especially after a hair transplant should be part of your MASTER plan for your future. 

If you suffer from genetic hair loss, then it is progressive.  However the progression usually slows down as you age.  If do decide to do hair transplant, it is best to make sure that the hair transplant is done by an experienced hair transplant surgeon.  The hair loss progression should be taken into account and the design should be done accordingly.  If done correctly, you should not have patches after you lose your native hair. It should look a bit thinner and to get it dense you may need to do a second transplant.  Another thing to consider also is to make sure the surgeon saves some of your donor hair for future use.