So grandparents can get around to use a skype app on a smart tv that has clunky interface. All smart TV interface and interactions are slow and terrible. If someone can learn to use smart tv apps, then for them a Xbox, Roku, Fire TV speeds, usability are a god send. From the looks of it, only Samsung out of all the TV manufacturers seems to offer a skype app running on a no name unpopular OS. If this was discontinued support on Windows, iOS or Android you will see a big backlash due to user base.
When was the last time you actually USED a smart TV? Every smart tv I have had experience with, in the past 3-4 years has been really good. Perhaps in the VERY early days it was like you described but recently that hasn't been the case.
I have some reasonably savvy older customers, but I can't see them a) shelling $500+ for an xbox to get Skype (see b) , and b) adjusting to ALL the stuff that an xbox CAN do for them. Maybe your Grandies are super up with it, most it's as much about willingness to learn as ability.