This leak has really made me happy. Looking forward to more info when it officially gets announced on Goku Day.
In regards to the actual contents of the film, as ridiculous as it sounds, a very small portion of me believes it's going to be a Moro movie, either condensed, or retold/revamped.
If they were to do another movie with some random new villain, what would they do with the Ultra Instinct situation? DBS: Broly had a pass because Goku had zero training or progress with UI after the ToP. Aside from that, in Broly, we just had Goku fighting with Blue or fusing to become Gogeta. Showing Goku fighting with Blue as his maximum state or showing Gogeta again (as cool as he is) would be kinda lame since we just seen him, and Moro/Granolah arc has already shown that Goku's past the need for Blue at this point. Moro arc is what shows Goku's progression into trying to master UI, and Granolah arc currently has Goku trying to go take UI into new heights.
Adding some random plot with no progression to UI whatsoever would feel clunky imo. On the other hand, if the movie features a new villain and it tries to add UI Goku progression, it would just make the UI training in Moro arc redundant if they plan on adapting Moro arc in the future. Another scenario would be if Toei never adapts Moro, whether in the upcoming movie or if the anime never returns, but not only would that be almost completely unlikely, if they wanted to adapt Granolah, it would have its own issues since Granolah arc starts exactly where Moro arc left off.
At the same time, tossing Moro into a film when it could easily be adapted into 16+ episodes for the anime would seem like a waste. Who knows man.
Obviously this is all just huge playful speculation
I mean there's literally nothing to make a judgement of yet, I'm just ecstatic we're finally getting new animated DB content that isn't Heroes.