I'm actually getting tired of the whole renewal ordeal, because if series like Jessica Jones and Luke Cage gets second seasons, it'll probably delay Iron Fist even further.
There's nothing to delay, in any case. No cast, no concrete pre-production, nothing. All we have is Joe Quesada saying it's "being worked on."
Any announcement at this point will probably point to a 2017 release. I'm writing 2016 off for Iron Fist, based on the turnaround time with Daredevil and Jessica Jones.
They could announce production commencement for Summer 2016 with an early- to mid-2017 release. Summer next year seems like the most realistic option IF they get their things in order by early next year.
That would not be as much of an issue if they have a showrunner attached and someone cast in the role. Like, I can easily see Netflix feeling good about expanding their lineup all year round with more Marvel stuff. It's not an issue to them. The bigger sign that Iron Fist is in trouble is just that it's taking longer than it should for them to lock talent into the project, which indicates they're not sure how to proceed with it.
This. Forget delaying, the bigger focus should be "where is everyone?" with the production team.
If Marvel plans things well, I can see them release The Defenders by 2018 or 2019. That gives them time to release a second season of Jessica Jones/Luke Cage (together), and squeeze in a season for both Iron Fist and The Punisher.