This is from Avatar 3. Look at that. RDA has a ship that makes SeaDragon look like a toy. And it's escorted by at least 5 SeaDragons, and I think 4 Dragon airships (including one standing on it').
The Sullies were never going to be able to live in peace in Awa'atlu just because they won one battle. RDA was never going to give up - no matter whether Quaritch lived or died. They were always going to come back with bigger guns.
This is from a teaser to the new Empire Magazine feature on Avatar Fire and Ash:
As production designer Ben Procter promises Empire, in Fire And Ash “we’re going to see an airborne and water-borne battle for the ages, as the Pandoran forces and RDA clash in a really interesting environment”. It’s a face-off, he says, that makes The Way Of Water’s end battle look like “nothing but a skirmish”.
RDA is even more tooled-up this time – bringing along a gigantic, smoke-belching Factory Ship (“Essentially a moving oil platform that is designed to capture and process the tulkun on an industrial scale”), more than twice the size of the SeaDragons. “Coming out of these vehicles is an army, and all of that leads into a war,” says Procter. “At the end of Avatar 3, what we’re going to see is something of a scale, in terms of conflict, that we have not seen before.” Payakan had better have some new tricks up his fins.