What would Kane merchandise be? A sled? Anyway TV, these days, hardly ever shows older movies with the exception of a small handful. It's on TCM all the time. The reason it wasn't a big success in its own day is because it was hindered by William Randolph Hearst's media machine. He wanted to buy every copy and destroy it.
Merchandise is any possible memorabilia of the movie. There are tons of posters and tinplates and such that you can buy, never mind even more mundane things like magnets, mugs and other household items as well as "conversation pieces".
Your view won't shake my impression of over 30 years. It was *never* a big deal in my lifetime; I am well aware of the changes in TV and media options from then to now. Only mentioned in some text books, especially film classes where they love it, of course. Had to see it in a liberal-arts basic film class (I'd seen it before).
Along with a true masterpiece like "Singin' in the Rain". At least they had some perspective of true greatness! ;D