Note: This is just a fun speculation, I actually don't think they are going to add any new ones.
I would like a Grey Jedi or an Technician. Playing as a balance between the dark and light side of the force would be good for those people who want to play neutral, yet not miss out on any rewards. (Obviously it would be game breaking, but this is just for fun)
Technician because who wouldn't want to work with droids, break into buildings faster, and fix your own ship and gear?
Also, smuggler doesn't really fit in the republic. I mean, smuggler would be more likely to help out the republic than the separatists, but still...
So, what are your ideas?