Probably not feasible, but what about having private outposts? Nothing fancy like a Fleet Starbase, but make it so a Vice Admiral could send out his/her officers to do patrol or exploration missions, and possibly side stories/quest. One officer could be promoted to Captain, and it would give us a reason to keep some of our lower tier starships.
Hmm... Could require a whole world of new grind possibly...
Its a nice idea though, could be made to tie in with the rep somehow perhaps but I don't see it happening.
Not to say I'd be averse to the idea from an RP point of view.
Could definately tie in to THAT side of the game if and when it comes for sure captain data. In fact I do see something (though not exactly as the OP describes) as happening someday perhaps.
Good thinking batman