Even if The Last Knight continues the downward trend domestically, that doesn’t mean the movie is going to do anything close to bombing.
Transformers: Age of Extinction may have grossed a lot more in its previews than The Last Knight, but Extinction itself was down significantly as compared to the rest of the franchise.
The last two films in the franchise broke $1 billion around the world, there’s no reason to believe this one won’t as well.
While this might appear to be bad news for a franchise that is currently planning several future movies and an extended universe, it’s a bit early to write off Transformers.