Having only played 1v1, I find it hard to fathom the 2v2 game being more than 1v1, except now there’s an extra person to push around tokens.
For future expansions, I hope they just don’t go down the more complicated route for complications sakes. The game doesn't need to include every variation of the TIE starfighter. It needs to continue to be narrative-based.
But it would be great to see a true 3+ player game. Here are a couple suggestions:
More factions
The addition of the Scum and Villainy faction immediately comes to mind. They would have their own objectives, missions, vehicles, etc. with their own win-condition, like collect the most money.
Alternatively, Scum and Villainy can be split up into separate syndicates, Black Sun, Hutt Cartel, Crymorah Syndicate, etc.
There are also a number of independent governments that were subjects to the suzerainty of the Empire. This includes as the Corporate Sector Authority, Hapes Consortium, Trade Federation and Chiss Ascendancy.
Traitor mechanic
Allow 2+ players on a side, each with their own secret objectives, one of which might be a traitor.
So there could be 3 Rebel players, each playing a Rebel cell with their own leaders. One of them has the possibility of being infiltrated by an Imperial Spy.
If it’s on the Imperial side, then one of the players could be a Rebel sympathizer.
Could also work for Scum and Villainy.
Another element needs to be added to keep players guessing. Something like Mission Gear. To resolve every mission, players must submit a Mission Gear card that could help or hinder the mission. A number of face-down cards are also blindly introduced to this mix. The Gear cards are secretly shuffled to ensure anonymity and the results are shown. (similar to Battlestar Galactica)