I think the best Chicago TV series would be about the late 1970's. Corruption was still rampant, they still had vegas, the bosses were still powerful and they still controlled politicians, judges, etc.

A period piece about the 1970's outfit would be great. Sopranos meets The Wire meets Mad Men.

There's supposedly a Chicago mafia drama pilot being pitched to one of the cable networks. Called "Pressure Cooker" possibly.