Genocide is too deep a topic for TLBT. Racism and xenophobia, or in this case, speciesism, has been an overall theme, throughout the first movie and a lot of the sequels.
If I was a producer or a head of Universal I would never associate genocide with TLBT, it would most likely kill the franchise.
Most of us here are probably young adults who grew up watching TLBT, and we would like to see something in a darker tone and with a more mature theme to it, but this is a kids franchise, targeted for small children, it's not like an anime where you can go nuts and kill the entire planet if you want, because your audience is just too young to understand or to even grasp the consequences of such an action.
Now, there could be guest characters from a species that's on the brink of extinction, and we had that with Sue in LBT X, and a bit with Doc in LBT VI. That's a concept that makes sense for children to start learning about at a young age, especially today where we are seeing one of the biggest extinction level events since the global extinction of the dinosaurs, and it's being caused by human activity.
I grew up watching cartoons like Denver, the last Dinosaur, Widget, the World Watcher and Captain Planet. These days there doesn't seem to be a lot of media directed towards kids that discuss these issues, like species going extinct, climate change and the effects of pollution. Maybe it's lobbying from big oil in the US, but still, it's a theme that I would like to see being explored in TLBT.
But I digress. This topic made me think about the first movie and how the herds had to leave their lands in search of the Great Valley because of a food shortage. How is the world outside of the Great Valley? Are dinosaurs becoming extinct? Was that event of the first film localized to a single region and that’s why we keep seeing other herds and wanderers coming to the Great Valley?