doesn't add up to reveal the endgame ship in a trailer and put off a large portion of the fanbase. They tailored it and left it open-ended for a reason. I think they're being purposefully deceptive to create hype and curiosity.
But the thing is that type of hype only works if the suspense is kept up until the movie release when the hype is confirmed to be false (or even confirmed true) a whole month beforehand it leads to anger, death threats and hate towards the creaters. or just uninterest to the movie.
This is a big gamble they are making, how many times do you see people complain when they are told or read a spoiler, and will say something like 'Great now the endings ruined for me, no use watching/reading the rest of the series.' I could understand if the actual story seemed unique but it sounds allot like the other Filler movies, only this time the main villain is related to the story villain and the princess to rescue is not an OC.
If they conclude in the manga, the movie would only be interesting to people who want to see how their pairing happened, not even those who want to see their pairing happen will care as much. They got the ending they wanted no use spending money on a ticket, popcorn and drink when you already know the conclusion.