I think that mining should play more of a part in trading, and factional activities (and capital construction until that is phased into purchase). As of now, there are plenty of worthless mining belts that play little part in the gameplay.
My idea: Create 2-3 mining areas TOTAL throughout the galaxy. One in rebel space, one in Imperial space, and one possibly between the Hutts/Corsec. Give each area one important mineral, and have the major sell-point for these minerals be in locations that are owned by other factions. For example , a mineral in Sullust that sells the highest in Muunilist.
This isn't the greatest example, but the concept is that faction-aligned miners would need to either sell their minerals to a civilian/neutral transport that is capable of flying through enemy space, or risk using a civilian character for the whole process and being hassled by the other faction once they are identified as supporting the "enemy"---
Additionally, faction miners and traders could schedule "mining raids" into enemy/neutral fields, bringing escorts to fend off the NPCs and hostile players.
This system would be a more peaceful version of a 2 or 3 way inter-factional drug smuggling system (which should also be implemented/enhanced to give independents/smugglers more to do). It would create some fun scenarios, and generally give both factions and independents more things do DO out in space, and more reasons to interact with each other.
The balance would be somewhat tough, as the Imperials are effectively cut off from Hutt/Corsec space and rebels would thereby be able to control 2/3rds of the fields, so maybe two total fields would be best. Or have 2 fields and 2 sell points in the northern part of the galaxy that would force a run through Dathomir/Kashyyk--giving each side a restricted checkpoint system, combined with 2 fields and 2 sell points in the southern outer rim belt, allowing main faction interdiction from the reb/Imp systems down there (as well as a high risk of pirate interference). The key to balance being the requirement to go through at least one "funnel" causing the likelihood of player interaction (or of course flying the long way and spending an hour to sell cargo in order to avoid players).