If TV Manufacturer's were smart, they would make the box sort of like a Cable Card -- where it is replaceable if something should go wrong with it. It would be pretty sad if after a year of using the TV the built-in cable box device died, and you had to buy another $2,000 TV.
But wouldn't they be smarter to leave it integrated fully, so that if it dies when the warranty is out that you would have to buy a new one?