We've been getting two shows a year and it looks like it will continue at least through 2017.
Luke Cage is already scheduled for September 30th. 2017 will see Iron Fist and The Defenders. It will be 2018 before we get a third season of Daredevil, a second season of Jessica Jones and the first season of The Punisher.
But fans of Daredevil and Jessica Jones will be able to get their fix in the Defenders series where those two heroes join with Luke Cage and Iron Fist to save Hell's Kitchen.