I doubt it'll ever happen.
I guess you could argue the Eternal Alliance is the third faction but for me I'd like to play as either the Hutt Cartel, Zakuul Empire or Chiss Ascendancy. "FOR HOUSE INROKINI!"
I don't remember where I heard this but the original plan supposedly would have had Zenith connected to the Star Fortress on Nar Shaddaa. He would have been the contact instead of the squid lady.
Lore wise Balmorra actually did have a Star Fortress. It was destroyed by the Shroud. The Exarch in charge of it was captured and appears in the KOTFE bonus chapter. Whether or not Zenith had any involvement in it is unknown.
I thought it was pretty good. The only part I didn't like was waking up to find Lana Beniko once again in my character's face.
More Vaylin is always a good thing. I'm looking forward to seeing where that plot will go.
Don't feel bad. Theron's actions resulted in the destruction of the Gravestone and the Eternal Fleet! He brought that on himself. It would have been nice if Lana grew a spine and opposed our decision during that scene.
The Scions from Zakuul send you to fight giant robots. You then go and fight these giant robots. After the fourth giant robot is defeated she uploads herself into one of the Gemini droids and helps you defeat the last giant moth robot.
Had he offered at the time my Chiss Inquisitor would have joined him. Now? I doubt it. From my POV the Empire is in a position of power under Empress Acina's leadership. I have no reason to side with Malgus nor do I have any reason to oppose Empress Acina.
* Dathomir - I want to see the Kwa and the gateways! (And the Rancors!)
* Lok - I want to see the Kimogilas!
* Dagobah - I want to see T7 get swallowed by a giant fish then spat out into the air!
* Malachor III - Maybe use Malachor as the location for what would have been the 'Emperor's World' ?
Going by her comment about being dragged into the scenario by the Outlander I'm going to assume Vaylin was stuck inside the Outlander since the end of KOTET.