Do you think are you going to implement the possibility to include alien soldiers in player's team in the future?
I say, it would be very cool to have one taman or ortnok playing in the good side... maybe, in the late game, the player can come in contact with some rebel force of aliens not infected by XVI, and make an alliance with them.
Maybe the player could find some slaves during a special rescue mission, and help them. Or, after discovering an antidote to the XVI virus/worm, he can be able to save some of the aliens he captured.
Or maybe, after deciphering the Astrogation system, the player can find informations about the location of free tamans fighting XVI.
The aliens could have some special bonuses in using alien weapons; and they can be available on a limited number, maybe you can introduce a single new NPC which is the only alien survived to XVI, and he has to go in some specific missions, and the game will be lost if he gets killed.