I'm afraid that this dates me, but I was at university when the (in)famous Heidi game
wasn't completely broadcast.
Any broadcaster who remembers that one won't ever dream of prematurely stopping coverage.
That was before my time, but I have heard of that incident. And although I am not a sports fan, I do believe that once a sporting event has started, it should be broadcast to its completion. It isn't fair to the sports fans to have a game interrupted just as it is building to its exciting conclusion.
In my opinion, the solution is to allocate a sufficient and realistic amount of time for the sports broadcast when the programming schedule is originally planned. Then schedule another half-hour or hour of fluff filler material at the end of the game to accommodate games that go long. Something like Gilligan's Island reruns. Or better yet, just include an after-game report. Sports announcers can easily stretch a five-minute game summary into a full hour of stultifying detail that, despite my dislike for it, sports fans would actually enjoy.
However, this will never happen. Why? Because of money, of course. The broadcasters won't throw away good advertising slot dollars on Gilligan's Island re-runs when they can essentially double their audience by running the games consistently late. The sports fans continue watching the game, of course, and the other viewers who tuned in for the regularly scheduled program will watch the game too, hoping that their show will be aired in its entirety.
Anyway, that is the short-term gain. In the long term, the broadcasters end up alienating the fans of the regularly scheduled show and inadvertently kill that show (e.g. Futurama). But, like most humans, broadcast executives have a hard time looking past the short term to see long-term consequences.