This week, two minutes of video struck both terror and cheer into the hearts of parents worldwide. The dread, for those with small children, is prompted by the endless viewings, deluge of merchandise and earsplitting singing that lie in store with the release of a follow-up to Disney’s blockbuster Frozen later this year. The trailer offered the first, teasing glimpse of that sequel.

The original is the highest grossing musical and animation ever, earning $1.3bn at the box office since its release six years ago and vast sums via associated paraphernalia. No wonder Disney wouldn’t let it go. It is “a generational set text”, wrote a Guardian critic: it is to its younger and mostly but by no means solely female audience what Star Wars was to teenage boys. Very loosely inspired by a Hans Christian Andersen story, it follows a snow queen who freezes the land and a brave young girl who risks her life to bring back the warmth.

This is a Disney princess movie that inverts or demolishes most of the tropes of that genre, and does so well and wittily enough that many will welcome its sequel. Though there had already been a broader shift away from classic fairytale storylines, Frozen proved beyond question that it is possible to make a hugely popular movie that eschews stereotypes and takes self-realisation, and the love between sisters Elsa and Anna, as seriously as romance.

The parameters of princesshood were once so narrow that The Little Mermaid, in which the heroine is literally voiceless for much of the action, was considered progress. It is not coincidental that Frozen was the first Disney full-length animated feature directed by a woman, Jennifer Lee, and that Kristen Anderson-Lopez, who co-wrote the songs with her husband, shares her feminist sympathies.

Frozen has its disappointments: notably the Barbiefication of Elsa as she comes into her own. Unlike the more recent Disney heroine Moana, the sisters are white and wasp-waisted. But this is a movie that, as those campaigning for a girlfriend for Elsa noted, embraces difference and shows the damage caused by shame and concealment. These are princesses who do the rescuing, learn to love their power, and wonder whether they’re “elated or gassy”. The handsome prince who sweeps you off your feet may be a frog. The companion who has your back is a better bet, but not the be-all and end-all. Your relationship with yourself, or your sister, may be more important. Frozen doesn’t just pass the Bechdel test with flying colours. It even rejects the Manichaean worldview of classic Disney movies: “People make bad choices if they’re mad, or scared, or stressed.” In another movie Elsa would be the villain.

We will soon find out whether what comes after Frozen’s happy ever after proves as pleasing to audiences. It will be a relief if the sequel lives up to the boldness of the original – and better still if Hollywood takes note of its lessons when producing movies for grown-ups, too.