Sincerity hasn't entirely gone away. You just have to know where to look for it.

Greta Gerwig and Christopher Nolan were always masters of it. Nolan is one of the few filmmakers I know of working who completely respects the intelligence of his audience and trusts (perhaps a little naively) that they can follow his often very complicated films. Spielberg over the last decade has grown sincere in his more serious films and until recently they could make big money. Villuneuve and Ridley Scott still believe in sincerity and respect and it hasn't hurt either at the box office that much.

The problem is, of course, how much the audience wants sincerity. The fact that Oppenheimer was the biggest box-office hit last year and that people went to see Barbie that same day seems to give a promising sign. We'll just have to see if it holds.