Whoever wrote that article isn't very smart. They have the same problem that most who think tax rate increases bring equivalent tax revenue increases, the old "all other things remain constant" argument which almost never holds true.
In thier point #2 they say you can't cut prices after opening weekend, then people wouldn't go to opening weekend, it would destroy the meaning of opening weekend. "The meaning of opening weekend". Who cares, other than maybe the movie studio for bragging rights about the meaning of opening weekend. The theaters and movie studios #1 priority is & should be to make the most profit possible. Now we already have discounted movie prices, if you want to wait X weeks for a movie to go to the discount theater, or a couple weeks more to get the DVD or watch it online. You should set the price that maximizes your profit, and most who watch a movie opening weekend, are there because they want to be the first to see the movie and tell there friends about it, and you can likely charge more without losing many of them. I don't know about $50, but I bet a $20 ticket for big movies wouldn't affect attendence.
Point #3, their concern that people wouldn't attend the cheaper movies. Why do they care. Again, maximize profits. Just like many people ignore (if not go opposite) movie critic ratings, many would also ignore the pricing structure as a guide for the quality of the movie. I actually expect there are many that don't watch movies at the theater because a $12 ticket isn't worth it to them, but a $6 ticket would be. So in reality, the $6 movies would probably sell better than they do as $12 movies.
And, the article doesn't mention the biggest drawback to variable movie prices. The potential of people buying a $6 ticket, and then going to the $20 movie. So instead of having a single ticket check station, they would have to have one at every movie room (or at least at every higher priced movie room. I still think they could make a profit though. A theater with 20 screens, at any given time could have 5 $20 movies, 10 $12 movies, and 5 $6 movies. They could locate them, from cheapest to most expensive, so would need 3 ticket stub checks instead of 1, so would have to hire 3 times as many people for that one job.