i suspect it's a long shot we'll ever get a return to class stories but i thought it worth a shot to throw these ideas i've hd up now that i've seen you have a suggestion box.
Zakuul Knight: it doesn't even need to be a full 1-50 story just a prelude and a chapter or two that take place during the invasion of the galaxy to give us the zakuul perspective of things. it may require some tweaking to KOTFE/KOTET - 'the outlander' becomes 'The Traitor' or 'The Fallen' or something. as for specs i'd say Tank: Sword/Shield and Damage: Saber Staff.
Imperial Legionnaire: i don't know if the engine can handle it or even if you guys want to ever do it but this game could be really fun with a pet class. my suggestion is semi-asymmetrical with the Imperial Legionnaire being a Sith side trooper in story feel. equipment wise Rifle or Heavy weapons because no one sith side can use Heavy weapons. the way i see the pets working is that each companion comes with a small squad of their own so companion 1 is Imperial Light infantry, 2 is normal infantry, 3 are Pyro troopers or something and so on. for ship i'd say the http://starwars.wikia.com/wiki/Imperial_shuttle is about the same size as the trooper ship it just needs a different interior then the one presented during the agents chapter on corellia or heck - have it be one of those wingless drop ships as the model on the planet and have the legionnaires 'ship' just be the troop deck and hanger of a Gage class transport or a Terminus.
SIS Operative: the second pet class, a republic side Agent with either single pistol or sniper rifle (no one Republic side can use sniper rifles) and perhaps stealth. rather then calling on republic soldiers the SIS Agent can call in droids or local militia types. i haven't put a ton of thought into the SIS Operative because as far as story and general feel i think it should just feel like Imperial Agent......with out the brainwashing but WITH droid minions.
Like i said i doubt any of these will happen but i personally would love a return to story content - i'll even do Voss again on the Republic/Empire characters if i can get a proper pet class for both sides and 3 more chapters of good story telling with new mechanics.