It was always Marvel's plan to release four series based on characters from its comics with Daredevil, Jessica Jones, Luke Cage, and Iron Fist, and that plan appears to be going well. However, there is a question of a release date on these shows, and precisely how they will all tie together when all four main characters will branch off into their own series known as The Defenders.
As far as Daredevil is concerned, it looks like Matt Murdock (Daredevil's real name, played by Charlie Cox) is going up against The Punisher for the most of Season 2, according to Realty Today. The Punisher is one of Marvel's notorious vigilantes, and even though he isn't a villain, he is hardly a hero as he will shoot to kill criminals. It will be interesting to see if Daredevil can bring justice to a character who might be bringing too much justice to Hell's Kitchen.
In addition to The Punisher, Daredevil will have to face up against Elektra, who will be portrayed by Elodie Yung. Elektra Natchios is a costumed crusader who also tends to fight in her own way, and she has played both hero and villain in the comic. She has also been a love-interest for Matt, and there was a possible reference to her made in Season 1. It is possible that she could appear as some sort of "love from the past" on Daredevil.
Considering that Jessica Jones finished its first season last week to critical acclaim, Movie Pilot is speculating some kind of tie-in to the next season of Daredevil, which will be premiering on Netflix early next year. Season 1 of Jessica Jones established Claire Temple (aka "The Night Nurse" played by Rosario Dawson). Claire has seen what Luke Cage (Mike Colter) can do, and she knows Daredevil very well and mentioned "The Man Without Fear" to Jessica.
There is also a "lawyer connection" as one of Jessica's friends is Jeri Hogarth (Carrie-Anne Moss). It would be very easy to create an episode of the show where lawyers Matt Murdock and Foggy Nelson (Elden Henson) meet with Hogarth in court. With Jeri's secretary Pam (Susie Abromeit) killing off Wendy (Robin Weigert), it would be quite easy to bring in that legal element as a story on an episode of Season 2 Daredevil as another thread that will connect these Defenders.
The next new Netflix Marvel show is Luke Cage, which will take place chronlogically after Jessica Jones, but will still focus on the man's origins. According to Latinos Health, the show will premiere later in 2016, and it will feature comic-inspired character Misty Knight (Simone Messick). Rosario Dawson will again reprise her Night Nurse role, and also appearing is a rival named "Shades" Alvarez (Theo Rossi).
As far as the next show, Iron Fist, is concerned, it is the one that we know the least about. So far, there isn't even a release date or cast for it, and it has been rumored that the series is being deliberately delayed because Marvel wants to test the waters for a possible series based on The Punisher. This is assuming that fans respond to him positively in Daredevil Season 2.
Then there is always the big question of the plot of The Defenders. It looks like Marvel's plan is to tie these characters together in a very subtle way, but introduce something that will bring them all together. What that is, we will have to see.