from the POV of the customers who want have portraiture done, what they really want is something physical to display their portrait, the only sensible choice is let the portrait studio take care of everything.
if they need some additional prints or any replacement, to ensure the best quality is still just go back to the studio let them take care of it. For such customers, they do appreciate high quality products and services, and willing to pay a premium for it.
On the other hand, I notice for some people who only want the softcopy to print on their own, they may use the cheapest mean to print it so that they can print every single photos from the session, or upload all the photos into their blog, facebook etc.. usually they won't go to portrait studio, they will find any photographers who able to offer them softcopy at the lowest cost.