During New York Comic-Con 2018 there was a panel dedicated to Gotham which recounts everything that has happened up until this point, ahead of the final season arriving in 2019. During the panel it was revealed that Bane would be featured in the new season, played by Shane West.
Gotham's final season is going to be based on the "No Man's Land" comic book arc. It takes place shortly after Jeremiah (Cameron Monaghan) blew up the bridges to the city, essentially cutting it off the outside world. Since then Gotham has been split into territories ruled by villains.
At the heart of the city is a small green zone right that Jim Gordon (Ben McKenzie) and the GCPD are keeping safe. However, The Penguin (Robin Lord Taylor) has taken over City Hall, Poison Ivy (Peyton List) ruling Central Park, and the Riddler (Cory Michael Smith) making the Gotham Public Library his home. Excitingly, the panel also confirmed that, finally, Batman will be making an appearance.
As of yet a Gotham premiere date has not been announced. All we know is that the final ten episodes will air sometime in early 2019 on Fox.