Despite growing optimism for renewal over the past few months, 'Luke Cage' has officially been cancelled by Netflix. Variety reports that there was a third season in the talks, but Netflix decided against it.
Unfortunately, ‘Marvel’s Luke Cage’ will not return for a third season. Everyone at Marvel Television and Netflix is grateful to the dedicated showrunner, writers, cast and crew who brought Harlem’s Hero to life for the past two seasons, and to all the fans who have supported the series.
As to why both 'Luke Cage' and 'Iron Fist' were cancelled, it could be due to the Disney App launching sometime in 2019, and has already confirmed to host original TV shows featuring MCU characters - Loki and Scarlett will lead their own series. Disney may be renew the series there. Another theory would be that both 'Luke Cage' and 'Iron Fist' were cancelled, after an improved quality for both this season, because Netflix is going to launch a 'Heroes for Hire' show starring both characters, something fans have been asking for years.
'Daredevil' Season 3 hits Netflix today, and a third season for 'Jessica Jones' has already been confirmed.