Generally in the US, the Owner of the property will own any improvements which the cable company makes to the property unless their was an encumbrance on the land title (or deed) - in which case their remedy for not allowing their use of the improvement would be foreclosure but would be in line behind all previously recorded encumbrances such as mortgages and covenants. This would historically include anything buried or running through the walls. Overhead wires also would likely fall in this category. Real property is funny that way.
Contrary to the article's implication, the cable company could retain ownership of the wire between the box and the wall socket. It's just equipment, like the box itself. But the improvements to the land convey with the land...if your neighbor builds his fence on your side of the property line, it's not his fence it's yours. That's why the cable company cannot insist you share your infrastructure.