Yeah, it may not be possible but hey, like the guy said, you can always dream! Hell half of these following ideas will probably take away from gameplay
And don't get me wrong, I love freelancer as it is
I like the idea of planet landing. Also have a humongous universe. Make it so that even though you CAN explore every aspect of everything, it would not be physically possible.
Imagine being able to walk into the 42nd story of a 50 story highrise open a drawer, take out a piece of paper, take the elevator back down, driving your car back to the space port, blasting back into space, flying 3 systems over and dropping the piece of paper on the alien planet with your name written on it.
For single player: Multiple storylines that you may or may not decide to partake in. Some storylines effect others.
Some storylines that may take place only on one planet/city
Trade: commodity supply and demand are effected realistically by everything that happens around that station/planet
Combining up with other ships more permanently than just "formation". Like actually make teammates and stuff.
A kickass AI for handling your teammates interactions with you.
Even larger scale team ups. I.E. wars
Maybe (since we're crossing games anyways) in a war during the campaign you can act as the commander and you'd control the field ala Homeworld although depending on the situation, your ships may not listen to you 100%
Customizing anything from your eye color to race to your spaceship/weapons/land car/pet to the clothes you wear