Does Star Wars: The Force Awakens book to announce the return of the beloved characters rather than providing any sense of plot. But that's not to say there aren't some details to be found.
One of the biggest additions in the Evan Rachel Wood and Sterling K. Brown have roles in the movie, but there's no indication that's who we're seeing here - although putting together what little we know presents an interesting theory: are they Elsa and Anna's parents?
Related: Frozen's Original Trailer Proves Disney Didn't Know What They Had
Going back to the original Frozen, Elsa and Anna's parents were King Agnarr and Queen Iduna of Arendelle who, as this is a Disney film, die during a storm at sea (although theories suggest they could actually be Tarzan's parents). However, songwriters Kristen Anderson-Lopez and Robert Lopez (via Variety) have said that, after Frozen 2, "we know the parents a lot better," indicating they have some role to play in the sequel. It's possible there'll be a twist that Agnarr and Iduna aren't really dead, although more fitting of the established canon would be a story-framing flashback. Is that what the trailer's "new" characters really are?
In the first Frozen, the mother was the spitting image of Elsa except with dark hair, the father thin-faced and light-haired; and, ss first pointed out by Bo Peep's reimagining in Toy Story 4). It's not inconceivable that this is their meet-cute. And if so, this could have some pretty major implications.
The theory would mean that Iduna has powers just like her daughter, albeit the ability to move leaves rather than create ice. It was said all the way back in 2017 that would help audiences "understand things better" in Frozen, and having Elsa's powers connected to her parents would definitely help explain that side of the story and make sure any increase in scale maintained a personal angle.
This theory does, of course, come from knowing very little about the plot of Frozen 2 and adjusted character design, so may be more limited than the scope of what directors Jennifer Lee and Chris Buck have created. That said, while there's sure to be a lot more to the film than just Elsa learning to control her powers and Anna grabbing Kristoff's sword, tying it back to the Arendelle royal family would certainly make sense.
