This could be the next Fellowship of the Ring
What I mean by that is based on research that i've done in regards to the production for both Assassin's Creed and Lord of the Rings there are some similarities that bear mentioning. Viggo Mortensen confirmed in an interview in 2014 that the production of Lord of the Rings was very messy, that Peter Jackson had spent a lot of money and that they were in a lot of trouble, even going as far as to say that the studio would never have allowed the expensive much needed reshoots for the second and third films and would have been straight to DVD had the first one not been so successful, It also wasn't till the first 20 minutes was shown at Cannes that there was any sort of confidence in it by the studio, and it was in fact a December release...
Now I don't know what the production for Assassin's Creed has been like for the cast and crew, but it seems as though the studio was a bit apprehensive about the film and reports say that the film is either 180 - 200 million dollars in budget which is A LOT, which is why they decided to screen the first 20 minutes to select press groups, and what followed were articles that were actually highly optimistic about what they saw. They also did do a first test screening as confirmed by writer Bill Collage, and now we've gotten another trailer, new posters, a TV Spot, and more behind the scenes looks at the film. I'm going to assume that fox now has a bit more confidence in the project and this is why I think it could indeed be a case like Fellowship of the Ring.
Because Fellowship of the Ring even with the problems they faced during production and admittedly not fantastic trailers, still released with massive critical acclaim and dominated the box office and in a time when the internet is not as prevalent as it is now. Assassin's Creed could turn out to be a similar case where there's a level of uncertainty about the project from the studio, the cast and crew are all passionate about it, and in the end it turns out to be a fantastic movie with the added benefit of brand recognition, the internet, and academy award recognised actors to boost its box office return. Oh and the fact that Assassin's Creed is also a December release. This is just a thought though, Assassin's Creed could turn to be a critical and financial flop absolutely, but let me leave you with this. Every big movie has the same chance to fail or succeed. Suicide Squad even with it's massive amount of marketing ended up being a critical dud and didn't make the money the studio was expecting. Assassin's Creed I still think is a case of waiting and seeing what happens, it could go either way, I'm hoping that it goes the right way.