I truely can say I don't have the answer.
![Smiley :)](https://www.carls-sims-4-guide.com/forum/Smileys/default/smiley.gif)
But whenever it will come out I don't think it will actually be recorded in the game itself. Despite the very cool camera angles and panning and zooming you can do it is still too much limited compared to 3D animation programs such as Blender 3D, which is free by the way.
Therefore I think that whatever they are planning to do there, it will be using objects from the sims (1, 2, 3, 4 or a combo of those) but added in a 3D animation program.
And I think you're right about the flop thing. As that is how many game movies turned out in my opinion.
EDIT: I wonder if this movie will be in English, or in Simlish with subtiles.
I hope the last one. Saves synchronizing for other countries outside the US.