The reason I think Shazam! may stick, is the fact it plays to every child’s fantasy.. Here you have some nobody kid, who suddenly has super powers. What child, or boy anyway, didn’t have that fantasy at one point or another... and here you have a story that plays right to that.
Hopefully their attempts to make it “contemporary” won’t ruin it, and let it just be a fun enjoyable ride of good vs evil.
If they do that, it could catch and surprise.
Looks like a superhero version of BIG.