I have ideas on who could be the villians in the fourth season of Gotham and some ideas on the plotlines.
Harvey Dent Becomes Two-Face: In the episode Harvey Dent, we got to see Harvey snap into his mentally unstable side while speaking with Dick Lovecraft. Like in the DC Animated Universe, Harvey suffers from dissociative identity disorder as a result of years of repressing his anger and his evil alter ego is named Big Bad Harv, which emerges whenever Dent loses his temper. While running against Rupert Thorrne for mayor, Thorne steals his psychiatric file and blackmails him at a chemical plant. This results in stray gunfire ausing an electrical fire explosion that damages the left side of Dent's body. This allows Dent to become the coin-flipping villian known as Two-Face with a vendetta against Thorne. I would like to see how Gordon would react to his old friend suddenly becoming evil and so he can experience it before Bruce Wayne ever does.
The Return of Hugo Strange: Thorne begins to feel that Hugo Strange's presence in Gotham is bad for publicity when becoming mayor, so he captures and tortures Strange after Strange turns Butch Gilzean into Solomon Grundy. Strange dies and Thorne has his body disposed of, however, he is haunted by strange visions and sounds of Strange. Strange is actually alive and tormenting Thorne with experiments designed to simulate ghostly experiences. That makes Thorne believe that his associates Commissioner Peter Paulings and the Penguin are plotting against him. Thorne kills Pauling and almost murders the Penguin until Gordon stops him. Also since Barnes is now longer captain, I like to see Gordon and Bullock dealing with another corrupt police commissioner and someone similar to Theo Galavan. I also would like to see Strange continue more with his experiments just like in the 2004 cartoon The Batman.
Selina Kyle V.S Silver St. Cloud: Silver returns to Gotham City and attempts to redeem herself by becoming a good girl instead of a bad one. She recieves training from her aunt Tabitha Galavan, however, she gets into conflict with Selina Kyle who distrusts her and is still angry at Silver for her past actions. I would love to see Silver become the show's version of the Huntress and face off against Selina again. I wonder how Silver would react to her aunt Tabitha training Selina and I wonder how Selina would react if she ever saw Silver again.
Bruce Wayne's Life Now that Bruce has become a vigilante, I would like to see how Alfred would react to it. At first, Alfred is not in favor of the idea of Bruce doing this, however, he eventually comes to accept the idea after Bruce protects Lucius Fox's mother Billie (who was originally going to appear in the planned television series Bruce Wayne). This can be like Smallville with Clark Kent being a teenage hero. Speaking of Clark, since there is a different version of Cyrus Gold in Arrow and another in Gotham (Butch Gilzean's birth name is Cyrus Gold by the way), this can be set on Earth 38 in Supergirl's universe where a young Bruce Wayne and Clark Kent would team up. This is what David Mazouz would want and this can be a good way to introduce the show into the Arrowverse. I also like to see Bruce make other friends such as Ethan Bennett and Vicki Vale.
The League of Assassins: Ra's Al Ghul comes back to Gotham with his daughter Talia. Since Bruce no longer trusts Selina, I thought it be good to introduce his love interest from the comics. Talia has an attraction to Bruce, however, she is torn between the loyalty she has to her father and the love for Bruce. I also would love to see James Gordon recieve training from the League of Assassins. That was an original theory on WMG and that's something I would like to see. A younger Gordon training with Ra's can be very similar to Bruce Wayne in Batman Begins. Alfred, who is like John Diggle from Arrow, heard about the League of Assassins during his time in the British Army too and thought it was a myth until now. A few Court of Owl members survived and will want revenge on the League of Assassins. I also wonder with 514A is.
Borrow Some Stuff From The New 52: In the New 52, The Joker's Daughter was introduced as a homeless girl who went insane and found Jerome's face. Hugo Strange could be responsible for that. She goes on a rampage and has an encounter with Gordon, the GCPD, or Bruce while he's wearing a mask. I also like to see flashbacks of the Court of Owls existing for a long while such as when they sent the Gotham Butcher to go on a rampage, which is what Amadeus Arkham discovered after hiring the bounty hunter Jonah Hex to investigate.
A New Joker: A man named Jack is introduced as a failed comedian whom Penguin refuses to accept in the Iceburg Lounge and becomes the Red Hood to support his pregnant wife Jenny. They make plans to rob a playing card company next to Ace Chemicals, however, during the evening, Alvarez informs Jack that his wife died in a household accident. Grief-stricken, the engineer tries to withdraw from the plan, however, the criminals pressure him. During a shootout with the GCPD, Jack falls into a vat of chemicals and dies in it. The Joker later on appears in Gotham, however his identity is left unknown and I like to still see Jerome stick around.