We're getting pretty close to the number of days that it took for the Part 4 Anime to get announced (127 days was the gap between the end of Part 3 and the teaser for Part 4). I'm guessing we won't get an announcement for the Part 5 anime until either: a) the Blu-Ray for Part 4 anime and the OVA gets released in Japan, or b) it will be a teaser trailer during the Part 4 live-action film that comes out in August. Which do you think is more likely?
I think it’d be more likely the first one; I don’t really see why they would promote the anime in an unrelated film.
Unless if you mean, like, an advert or something in the screening, which would be a little more plausible, but I’d still say the first one seems more likely.