In addition to the announcement of the trailer, Diesel also wrote, "You will see why there was tension, you will understand the intensity." It's a bit cryptic, so the exact meaning isn't clear. It could be a general commentary on how it was to film following Paul Walker's death. On the other hand, it could also refer to the reported feud between Diesel and co-star Dwayne "The Rock" Johnson.
The feud, which was brought to light following Johnson's comment that Diesel was a "candy ass," was never fully confirmed as legitimate. One rumor said that it was a hoax to promote a WWE wrestling match, which was plausible because Johnson is a pro-wrestling veteran. But that was only one anonymous source, so it could very well have been real. Based on this status it's possible we'll see a bit of closure, whether it's an explanation and reconciliation between two actors, or a played-up, over-the-top wrestling match. Only time will tell.
As for the trailer, the premier is in New York City, and Moviefone expects the trailer will be featured at movies soon after, possibly Rogue One: A Star Wars Story. The actual movie is also scheduled to be released on April 14, 2017, with two more scheduled for April releases in 2019 and 2021.