Here is my theory/something that I would love to happen but there is a very good chance it won't. I thought of this over a month ago
In the clearing of a forest (kinda like the one we see at the end of the trailer, all of the characters are gather together along with Rexy and Blue (with her baby, Beta). Rexy and Blue are facing down the Giga. The battle rages on, but the Giga is too strong for even the combined force of the raptor and rex. The Giga knocks Rexy to the ground and puts its foot on her, restraining the rex. Blue jumps on to the Giga but is thrown off, landing hard to the ground. The music builds as the Giga is rearing its head back to finish Rexy off, but then both the music and Giga stop. Everything is quiet. And then, from the trees comes a very familiar sound, da da dada da da da ( the Nokia phone ring). The Spinosaurus from Jurassic Park 3 comes bursting the the tree line and knocks the Giga to the ground. Rexy and Blue get up and fight alongside the Spino to help bring the Giga down for good.
This would be so poetic since we have seen these three dinosaurs fight each other throughout the franchise. Rex and raptors in the Jurassic Park. Rex and Spino in JP3. And raptors vs. Spino in the chaos theory for Jurassic World Evolution 2 (I know it's a stretch, but I think it still counts). We know that the Spino is alive because of the latest Camp Cretaceous season, so I'm hoping for it to make an appearance here.