Re: Batman v Superman: Dawn of Justice
More than widespread decline, I could more easily see transitions from one kind of comic to another. Traditional superhero stuff has come in and out of style over time. It waned in the mid-late '80s, and didn't really come back until the 2000s. In-between we saw gritty violent comics, bat**** crazy indie stuff like Grant Morrison's Invisibles, and thoughtful sophisticated stuff like Sandman start to take hold. I can imagine the same happening in comic films as cultural tastes change. Just like cinema in general, thinking about how films seem to react to the times, being optimistic, pessimistic, frustrated and repressed, excited and manic, etc. depending on what's going on in the world.
In some ways we see this now. Easy for me to understand why the X-Men movie succeeded more abroad than in the U.S., while GOTG was a huge domestic hit. Because they respectively connected better with those cultural sensibilities.