Technically, you are correct. But I'll try again. Suppose Apple does as suggested as adds a coax in jack to the

TV. Then what? I have DISH, so if

TV is going to be able to replace my DISH box, the software that translates DISH digital signals into something that can actually be seen on the HDTV will need to be built into the

TV box. Suppose you have DirectTV. Same issue. Someone else has Comcast. Same issue. Cablevision. Time Warner. Etc. There are lots of them.
In a Coax in solution, Apple would need to strike deals with all of these players so that the software could be put inside the

TV to work with their particular variation of encrypted digital signals over coax. Most (all?) of them make nice revenues by renting their own boxes, effectively a required rental if you want to view their signals. Why would they cut their revenue throats to make a one-time (purchase) box from Apple replace all that revenue (and related opportunities by installing their own boxes)?
I offered how it could work against that reality. Maybe adding an HDMI in port to

TV could allow all of the Cable/Satt players to keep their boxes in place while still creating a way for the signal to flow through the

TV4 (with HDMI in). I think this is much more likely than all of the existing cable/satt guys cooperating with Apple to kill off their recurring box rental revenues (and related revenue opportunities).