I know several people who started off with this plan, had one knee done, and after discovering how horrible that experience was, decided never to get the second done.
I've had surgery a couple of times, in my late teens and mid-20s, and nothing as difficult as a knee replacement. Coach K's dedication to his coaching is impressive. Most people would not have the drive and fortitude to commit to this again while keeping up with his professional responsibilities.
I hope the surgery goes well. There is no guaranty we will see Coach K on the sideline this year (or any year after) . . .