Hairline corners. Is this sort of transplant possible? (Photo)

Hair transplant may be an option for you but you need an exam to confirm this. You can see this from many before after photos.

You are absolutely correct - will you be needing to play catch up if you thin more in the future.You are very wise and you appreciate these risks. If you choose to address the corners you should consider the real possibility of a future transplant and hope for the best.It is never ever possible to predict a "one time" hair transplant in a man under 40. However, I strongly believe with any such hope to make this a one time thing an individal must be on medical treatment at the same time. Otherwise the probability or odds that you will need another transplant jumps up significantly.

For. Looking at your pictures you are a grade two on the Norwood scale of hair loss and you are a good candidate for hair transplant. You can see a hair restoration specialist and state your concerns,  hair transplant I the frontal hair line and the temples can be very natural if done by an experience hair transplant doctor. If there is any miniaturization behind your existing hair line, they can implant hair in those areas so that you do not need to play catch up and if your  hair loss progresses you still have hair in those areas. 

In a frontotemporal recession case, the only way to do a transplant that can stand on its own is to look at family history and correct for the worst case in the family.  Therefore,  if the worst case is loss of the entire crown of the scalp,  for you to transplant that area too.However,  I don't recommend that. I recommend correcting the frontotemporal area that is currently bothering you and using medical treatments to slow any further thinning of the scalp hairs. 

Yes, the hair line shape can be changed easily with hair transplants. Hair transplants can create any hair line you want. What your pictues suggests is a maturing hairline but you would need to be evaluated to get a straight answer. See galleries below

 It is certainly possible to transplant the corners of your hairline. However, it is likely you will recede more in the corners and towards the center of the hairline. Therefore you should plan to have more work done later in life should you choose to transplant the corners now.