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Was interested to see this in a novel (the author a fellow New Yorker, for what that’s worth). I’d never come across it outside of my childhood coterie. ‘Coming attractions’ as a synonym for ‘movie previews’. Because . . . at that time, previews were introduced by a slide on the screen reading ‘Coming Attractions’. And we took that, obviously, to refer to the teasers themselves.
You are invited to consider the broader point.

Not addressing the philosophical aspects of this question, but a report on ancient and current practices.

Our local "art theater" (located within the logical boundaries of the Brown University campus, but fiercely independent) still projects "Coming Attractions" at the appropriate time, although now it's (slightly) animated. (This is the theater where we go to see Casablanca when it comes around every year.)

After my freshman year in college, my summer job was cashier at a similar small theater (the "Little Theater" in Baltimore). But I never got to see the attraction that ran for the whole summer -- Brigitte Bardot in "And God Created Woman" -- I wasn't old enough to be admitted.

That’s nice! Retro-y in a positive way. Thanks.