Well there are several variations in the comics about Gordon, and the time between T.V series can be more than a year as well. This is how I see the T.V series panning out....
I can see him slowly chipping away at the police force, dismantling the overt mob corruption. Then cells within the Police force and so on over the years, but never fully cleaning out the police force. And as the years go by Bruce Wayne gets more and more involved.
I can also see him handling the major villains as they appear now (they have not matured into the real deal yet), Penguin, Riddler etc and starting the cycle of sending them to Arkham.
But some will elude capture, like Victor from the recent episode and be a foe who appears and disappears over time.
Ultimately, the combination of the mob and various *named* villains will start to win this protracted fight that has spanned at least a decade, and then Bruce realises that Gotham needs an extra weapon, and Batman appears....