When I said a third faction I don't mean a faction about a power similar to the republic or empire I mean a force like say the reapers or collectors from mass effect as in having a massive story behind them but with no need for more classes for the specific faction I think an excellent faction to add as a complete enemy faction to everyone(no classes needed for it) would be a resurgence of the infinite empire led by things such as the rakata box on tatooine that tried to use czerka to get back, or maybe even the architects the ancient race who came up with the hyperspace anomaly(in probably wrong on this bit of fact but I think I read it somewhere) a faction that's more advanced and more powerful than the republic or empire being a fanboy my ideal chapter 5 and 6 is a very long drawn out storyline beginning with each normal class being hinted that something rising outside of the republic or empire then after the classes' own personal storyline to reintroduce u to your character after the long time between expansions have a mass effect 2 like ending to chapter 5 leaving it on a note where you are trapped wherever u may be confronting the threat.
Another thing I would love is if they made the companions for each class essential in the storyline even treek and hk 51 something that engages you with your companions that makes you really care o saw great potential for the trooper ending against rakton instead of just storming the bastion if it had a massive battle say in space, above coruscant etc and when you went to face rakton with your chosen companion it should have had a moment when you were in doubt as a player as to whether your character would actually succeed like where tanno Vick and the rest are being overrun with imperials and the soldiers are being gunned down or something like it I hated how for the entire storyline u knew in the end you would succeed if there wad more uncertainty I feel it would have been better but I understand how hard it would be to make a storyline like thatb in a mmo
I suppose all we can do is wait and pray