Think of this as a what if you should ask yourself if you are considering surgery (especially strip).
If you look at this video you'll get a good idea of how small a donor area can get and how big a potential recipient area can be (donor section around 0:24s to 0:28s). Hopefully everyone can see that the potential recipient area includes the top, crown and large areas on the sides and there is no way that the limited donor area could provide adequate coverage for all of that.
Someone already advanced to this stage would probably be better off not bothering with a
HT. If hair loss really bothers them then considering a system would likely be a better option. If they have to have surgery then it should be extremely conservative with a very recessed hairline & leave the crown.
If you're thinking "my hair loss is not that bad". Can you be certain that you won't recess to that point? Propecia can wear off after a while and it doesn't work for everyone. If you have an aggresive surgery now will there be enough to fill down the sides towards the ears? Can you be sure it will look natural?
Also bear in mind that if the donor area looks narrow now it will look a heck of a lot narrower after 3cm has been taken out. (This would provide around 7200 grafts, assuming density 80/cm2, strip 30cm long) This would likely be over 2 or 3 sessions.
http://news.bbc.co.uk/1/hi/technology/8291327.stm
I don't think this guy's donor is unusually narrow. I do think that we can kid ourselves that things would never reach this stage.