Hm dunno, why should the movie guys bother with what's going on in the manga currently? I doubt that Miura will play a big role in the movie team and neither are they making a movie about the current events of the manga, so it should be totally independend from the current manga state.
Just timing, cause it's going to take more than three years so if they aim to say hey lets have it up to elfheim arc then that would be good. Clearly though the movie part V for example would not end at elfheim it would end after something happens in or after elfheim. Breaking the movie into parts, 3 hour movies wouldn't hurt
Lets see
*movie 1 has - vol1-3 then into the Golden age who knows maybe to the part Griffith becomes general.
*movie 2 - goes to the end of the Eclipse.
*movie 3 - would be huge that ends after saving Caska.
*movie 4 - would be till the end of the Witch.
*movie 5 - would be till Griffith/ Skull knight merges the Astral world.
They would prob have 6-8 months between the movies being released too. Gawd man, when the first one comes I am gonna watch it over and over. Note I hope each movie is over 2 hours, most Anime movies are 90 minutes...