The film will be a Compressed Adaptation of The Trench and Primal Waters
The trailer shows 3 Megs being active at the same time. With one being absolutely massive even by Meg standards. This is quite obviously supposed to be Angel from the second book. But (unless I'm mistaken) she was the only Meg in The Trench with a Kronosaurus being the main threat. Angel and her two offspring wouldn't be the main threat until the 3rd book. Here, it seems like the 3 Megs will be the primary threat with Kronosaurs being nowhere to be found. Though they could be saving it for a later trailer or a surprise in the film itself. Adding onto this... There will be a stinger revealing the existance of a Liopleurodon
Setting it up as the main antagonist of the next film. Which will be an adaption of Hell's Aquarium