New trailer for Depth

[Paddy™]

However, the release date, the feature type and title were not things that were set in stone or confirmed and were largely assumed by people.

Everything ever said about it anywhere by anyone involved with the production supports the idea that it's a feature film, and nothing they've ever said supports the contrary. The casting call labels it as a feature film - does it at all seem likely that a production company would falsely advertise their project to prospective actors? On top of this, Don Thacker has said that it's "long enough" [skip to 20:50] to possibly be shown in theatres. The film also has a theatrical ratio in its specifications on IMDb which the first two films did not have. By itself that might not mean much, but in combination with what Don has said it adds to a strong cumulative argument that it's a feature film, as does the simple fact of the production having taken over a year to complete, rather than the approx. 1 month needed for the first two films.

The existence and length of the film (regardless of how we end up ultimately seeing it, whether as short clips or one long film) is - according to all available evidence from those who would know, including the director of the film - not in question.