If we could alter the opacity of a camera’s view, it could allow for some awesome/trippy visual effects.
My vision is that one would be able to layer multiple cameras on top of each other, and then lower the opacity of the cameras from the top, so you can see through them and into the other camera views.
Change Camera’s Opacity
You can already achieve a very similar effect by layering multiple views pointing at different maps that contain transparent elements (such as actors, tiles, etc) similar to how you can layer interfaces.