Netflix and Marvel began a safe bet with four separate shows of Daredevil, Jessica Jones, Luke Cage, and Iron Fist, that take place in a (for lack of a better word) "grittier" side of the Marvel Cinematic Universe.  While Daredevil Season 2 is happening at the end of this week (starting March 18), and Luke Cage has an actual release date.  Some of the other shows like Iron Fist, Jessica Jones Season 2, as well as the Defenders don't have any specific release dates for now. 

Daredevil Season 1 focused more on Matt Murdock (Charlie Cox) assuming the mantle of the crimefighter in order to take on the ruthless Wilson Fisk (Vincent D'Onofrio), and it was apparent that some seeds of what will happen in Season 2 and on other Marvel/Netflix Defenders shows will happen. 

For example, Matt had to take on Yakuza agent, who was dressed like a member of the Hand, a ninja group inspired from the comic book source material.  Then there is a mention on Season 1 that Matt had some Greek girlfriend that is going to actually show up in Season 2 as Elektra. 

A recent trailer shows that Elektra (Elodie Yung) and Matt are going to be teaming up to take on a lot of members of the Hand.  It also looks like Matt and Elektra could become lovers again, and it is for certain that Matt's old mentor Stick (Scott Glenn) is going to show up. 

There is one wildcard that everyone is talking about, and that is the presence of The Punisher, played by Jon Bernthal.  The Punisher is also from Marvel's source material, but what makes him different is that he is more anti-hero than superhero.  While Daredevil Season 1 focused on how Matt went out of his way not to kill his foes (even though he was tempted to), Punisher has taken the other path.  The Punisher is out to kill criminals, and possibly Matt, if he gets in his way. 

Yes, that will happen.  What isn't clear from trailers is how the events of Jessica Jones have affected this Netflix/Marvel/Defenders universe.  There was a little bit of a crossover as Claire Temple (aka "Night Nurse", played by Rosario Dawson) showed up and saw Jessica as well as Luke Cage, but that was about it. 

As for Luke Cage, the strongman character who was introduced in Jessica Jones (played by Mike Colter), he finally has a release date.  Engadget reports that his show will be premiering on Netflix on September 30, which is about six months away. 

At this point, it is starting to look like Marvel is making a Netfix "gritty" show every six months, with Daredevil Season 1 appearing last year, and Jessica Jones last fall, followed by Daredevil Season 2 now, and Luke Cage about six months from now. 

Next on the list is Iron Fist, which has been cast with Finn Jones as the title character, but very little is known about that except Carrie-Anne Moss, who played Jeri Hogarth in Jessica Jones, will be appearing for at least one episode.  Given the track record, that places Iron Fist in early spring, unless Marvel and Netflix want to double up on the seasons. 

Speaking of doubling up, Marvel and Netflix haven't said anything about when all four characters will be coming together for The Defenders.  At this point, it's probably not going to be until 2017, and possibly later depending on if Daredevil Season 3 or Jessica Jones Season 2 will arrive.