We have an initial date for Digimon Adventure tri. part 4, but no title or even a teaser of the poster yet.
Via multiple people in Japan, it appears the initial date given for part 4 means we are in for a short and reasonable wait...
Update- Toei has confirmed the date also at this point.
February 25th, so we can likely expect streaming the same day.
No date for the disk yet, but early April is likely.
Thanks to C-MC for pointing this out.
Update- The title for Part 4 is 'Loss' (Kanji- 喪失 , Romaji- Soshitsu)
Update- A LQ phone shot of the poster.
It appears to show Hououmon, Sora, Taichi, Yamato, and Mugendramon.
Thanks to AlphaNinjaX for the image.
And tri. part 3 may have had a stinger/teaser for part 4, which is now confirmed as not existed.- Hikari vanishing and Takeru calling out to her.
Update- At least one person from Japan on Twitter is saying they made up the details of the stinger, that it what they hoped it would be (they also apologize as it appears they weren't aware their wording was unclear.)
Leaving the details up for archival purposes, but at this point we are sure it doesn't exist.
Update 2- ukyou has watched the film in Japan. There is indeed no stinger/teaser for part 4
Update 3- A significantly better image of the poster (not great, but at least low medium... which is better than the previous 'low' quality image.)
Thanks to a baidu user for the image, and for Neko for letting us know about it.