I still think that G5 is set so far into the future that almost no one we met in G4 (save extremely long-lived characters such as Spike and Discord) is still alive.
And even if they are alive so long after the end of G4, they are probably not long part of the mortal world with the possible exception of Spike. If the Mane 6 appeared, they would be immortal spirit beings as part of the ponies' common magical source in the mysterious dimension — for there is no other logical explanation for them to appear in the movie.
It seems that Hasbro has problems with its G5 toys, without a trailer that could elaborate on the role models, their background and action, there is quite a bit that can motivate outsiders to be interested in the G5 by themselves. The advertising campaign has now become too violent, and it is noticeable that it is not going well. Then the trailer must come out. If they were to wait "a little more", "a little more", without announcing when it will be out — and then almost until the movie comes out — sales may stagnate. Is now strongly convinced that Hasbro has made a big mistake by switching to Netflix.
People are starting to walk away. Interest weakens. Others gain attention. Even the fans are starting to get bored of it all. Should the trailer be absent for the next few days — it could be detrimental to the G5`s future. There are now only two months left until the movie.