If you start from first principles and you compute it as "2.5 hours of entertainment in a climate controlled and comfortable environment with refreshments", it doesn't feel unreasonable to put it at 30$ (per person): that's in line with how much other comparable activities will set you back (escape rooms, paintball, whatever).
If you go from "the price has increased too much since I used to go there as a child/teen" then you are going to say that's way too much.
Some (most?) movies do feel better in a cinema than at home (at least to me). And this is without considering 3d, immersive sound/vibration or anything, just "vanilla" cinema. "Everything, everywhere, all at once" doesn't have the same ooomph on my tv.
I don't see them dying but they are endangered and niche. Bit like theatre.