I'm a new TI player and I have to say that TI4 is fantastic.

I wouldn't be keen on a distant suns type mechanic - the game is long enough and complex enough already, and RNG is evil in a player vs game sense.
What I would like to see is minor races - but deployed at game start like the rest of the map.
They'd be on a single planet and you could conquer them or otherwise diplomacy them. It'd need to be dirt simple though, like a token with some requirements on it.

I really liked this from star trek ascendancy, even if that was the only thing I liked..