I think that's likely. The combination of the guaranteed income and the fairly low chance that many subscribers will actually use their pass every day means it isn't a big risk for the theaters.
Well, and the likelihood that the subscriber will bring at least one friend who would pay full price for a ticket makes this less risky. Also, popcorn and other concessions are the real profit drivers for theaters, so losing a bit on tickets isn't as big a deal as it might seem.