Not only are they renewing the original series, they have already greenlit a spinoff series for Jon Bernthal to star in The Punisher.
MCUExchange is reporting that Marvel and Netflix are currently casting for the character of David Lieberman, also known as Microchip/Micro.
Since then, Daredevil has had two seasons and a third announced, with a second season of Jessica Jones also being ordered.
Punisher appearing in The Defenders is something that could easily happen, given the friendlier nature that he and Daredevil had at the end of season 2.