It should be perfect simulation of Star Wars battle. The 6 movies atleast.
1. All the battles from the movies in realish scale. Some are bigger, some smaller
2. Better space fights with more detailed ship interiors and more vehicles. Possibly space-land fights on single map
3. You can join any team in multi-team battles (Sandpeople)
4. Troops have Republic Commando type gameplay with melees, ability to pick up weapons (you are weaker with ones you're not specialized in) and tactics and AI. Better 1st person view too.
5. Multiple heroes (up to 3? 5 is the maximum I can imagine)
6. Heroes have real health instead of timer
7. AI can control heroes
8. Jedi gameplay from Jedi Knight games, especially saber clashing is needed
9. Vehicles were ok in BF1 and 2
10. Great, varied soundtrack. Full Star Wars soundtrack unlike in BF1 and 2.
11. Able to play it simple like BF1. I dislike BF2 because of all the medal bonuses and options I have to tune.
12. A lot better campaign. Something like Jedi Knight, Republic Commando and Battlefront combined. You might have to infiltrate someplace alone or with a small team and open the door for your army and then have a huge fight etc. Coherency and variety instead of basic matches with "backstory"
Perfect last game.