Just for fun, I've given arcs for each character for a hypothetical season 3.
Matt is in jail, and must survive with many from the AVTF in there with him. Forced to fight for his life, he embraces his Daredevil persona publicly, and gathers inmates loyal to him through fear or past defences. This comes to a head in a big fight where Agent North dies for Matt, Agent Powell is beaten and Matt takes over the prison from the inside, embracing his inner power.
Karen and Kirsten try all they can to free Matt and adjust to NYC after the chaos ends. After their previous interaction, Karen looks for dirt on Heather, and discovers she's gone mad and is following in the footsteps of Muse. Karen uses this as key evidence that Matt was wrongly imprisoned, and must take down Heather without killing her to stop Muse becoming a symbol that's further passed on.
Jessica and Luke try to find a new normal after Mayor Fisk, and they explore the aftermath of Luke being a hero for hire (in exchange for the protection of their daughter). As they investigate a new vigilante they learn it's a Daredevil copycat. Initially they think it's Bullseye, but it's revealed to be Danny Rand, the Iron Fist. Keeping his identity secret even from them, his impersonation turns out to be critical in freeing Matt as Kirsten argues that they can't prove what Matt did and didn't do. Luke recalls his history to Jessica as they rebuild their marriage, and suspects Mr. Charles is more than just a CIA spook.
BB Urich uses her new role to explore Fisk's past and work out where he's gone. Using her uncle Ben's research and finding information left behind by Daniel at his family home, she travels across the country to find Kingpin, joined by a revenge-fueled Angela Del Toro (whose amulet powers are growing by the day). They find Wilson Fisk in rural Tamaha Oklahoma, where he's living in isolation and exploring his past thanks to the powers of Maya Lopez aka Echo. Stopped from killing on Lakota land, both are guided by the tribe to give up on revenge and embrace peace. By the time they are allowed to leave, they find Fisk is gone.
Fisk himself explores what a life beyond New York looks like. Confronting those he's killed and those he's lost inside his mind with Maya (like Foggy, Vanessa and Wesley), he decides to check in on his city, afraid it will fall into the hands of someone who doesn't love the city as he does. He finds that Mr. Charles and his agents are taking down crime families one-by-one. Fisk takes it into his own hands to stop it, inadvertently becoming a vigilante himself.
The main villain is Mr. Charles, who utilises the chaos and power vacuum to slowly amass power and defeat the main five crime families (including the Tracksuit Mafia). Bullseye is his agent of chaos, and Charles tries to recruit Buck (successfully), Melvin Potter / Gladiator (successfully) and Muse (unsuccessfully) to his cause.
With New York's turf war growing by the day, a historic trial of Matt Murdock begins. Allies from across his life like Cherry, Swordsman, Josie and more create an alibi for Matt, claiming that with multiple Daredevils it's impossible to tell what he did or didn't do. With Heather's testimony also thrown out and pressure from thousands of people claiming they are all Daredevil, he's allowed to go free.
Getting back to business, Matt reunites with Luke and Danny, and together the heroes fight off Charles and his army from taking over Red Hook. The truth is revealed: Charles is actually an agent of The Hand, not the CIA, with his ninjas flooding into the city. It's an all-out battle for the city. Matt defeats Melvin, and during an overnight siege forces him to alter his suit into a new Daredevil one. His suit embraces his power of fear he discovered in prison, a weaponised, samurai-like suit. The stalemate is broken by Kingpin of all people, who faces off against and kills Buck. The war resumes, and Bullseye turns on Charles after discovering the truth, killing him and escaping.
In the aftermath, a power vacuum remains in New York. Aware that crime will never leave the city, Matt makes a choice - he will become the new Kingpin, keeping the underworld safe by controlling it from the shadows. Matt and Fisk cross paths leaving the scene, and both realise that they have become the other in a way. Fisk leaves the city knowing it's in the hands of someone who will fight for New York. Fisk retires to the snowy isolation of Alaska, his final shot reminiscent of a rabbit in a snowstorm.
BB and Angela successfully avoid losing themselves to revenge, and Angela leaves New York to discover her ancestry and power from the amulet. BB runs a story on Fisk using what she's gathered this season, humanising and exposing him in an attempt to stop him becoming a martyr. The cycle is broken.