While I'm not against the idea, and it might be possible to have a dedicated "Imperial" job in the next xpac, an xpac centered around the Empire won't be the next on (We are about 95% certainly going to Ala Mhigo.)

The big thing about an Imperial job is, how would it work? What would the main weapon be, seeing as how the Imperials basically use the classes we have, with magic either being Tech-based or conscripted soilders. This leaves us with the higher-ups, like Gaius and Nero...which I think there would be many who wouldn't mind Nero being a Job teacher, more so since he would get a whole story-line dedicated to himself. Not sure if his hammer might be considered too close to MRD/WAR axes, but its a start.

Gauis/Regulus style could also work, giving a new sword class that might not neccesarily be a tank and being downright cool as well, but how exactly we would learn THAT style is much trickier. Possibly a Legatus who goes rogue in 4.X, and in 5.0 we learn from him/her?