Reposting from older threads:
If I were to write an Avatar setting, I would go for an attempt a symbiosis.
Imagine this, Eywa balance everything on Pandora, it's the ultimate synthesis of everything on the planet: everything is safe on a species scale. It's a solution to the issue of survival through symbiosis.
And then the humans came. They are not just a threat in themselves, they are the realisation that Eywa is a big fish in a small pound (or maybe the small pound itself but whatever). Maybe Eywa "realised" through contact with humans (maybe when Jake connected?) that its survival was at stake for the first time in Eywa knows how long. Humans, but also any cosmic disaster could erase Pandora and Eywa when it thought itself eternal. It rediscovered the need to spread to insure survival, this time at a galactic level.
After chasing of the immediate threat, I could see Eywa going back to its usual method: symbiosis. It need the humans to travel the stars, so it has to offer them something in return. Now the humans have ecological issues, something Eywa is very good at regulate.
So I could see an attempt at a deal between humans and Eywa: humans spread its sprouts and Eywa child act as biosphere control.
Striking the deal could be a movie in itself.
The rest of the series is then about teams of humans scientists and na'vi shamans trying to grow baby Eywa. With various success as each Eywa is going to be a different non-individual.
But also different ecosystem (polluted developed worlds, new colonies on a barely habitable planet, worlds with their own non-sapient lifeforms...), different teams and methods, different issues...