I was recently reading the Undead İron Fist run and I think this version of Danny could work really good as a separate character. And more importantly, one of the subs favorite things, he could easily be a Strategist.

For people who haven't read it or could use a refresher, all Iron Fists die on their 33rd birthday, and this comic revealed that that is because Quan Yaozu, one of the first Iron Fist, kills them to steal their chi to become more powerful. In order to stop him, Danny makes a deal with Osiris to be come his avatar, similar to Moon Knight, although with I time limit (currently).

With the basic information done, this is why I think Danny should be added to the game:
For starters, interactions. The worst part about Lin as Iron Fist is he had no history and his personality is just so bad in all of the ones they game him due to his arrogance. Adding Danny would allow for different interactions based on the character's history with the other heroes and villains. After that is the most obvious thing, the powers. Being the avatar for the Egyptian god of the dead and resurrection allowed him to do a lot more than throw charged punched. He is given energy that he uses to exorcise demon from enemies, but that also allows him to become intangible so he can phase through solid object and enemy attacks. His secondary fire can allow him to fire the Rays of Ra to heal allies while his main fire is a series of melee attacks. Then one of his abilities can allow him to turn intangible for a few second, essentially working like Wanda's ability but without giving flight. As for how he'd differentiate from Lie, I think he would simply attack slower and not be able to fly like he can in the game (at least not as much if at all). Danny would have slower strikes that hit harder. And he could be called Ghost Fist, which he was in the most recent comic, so they have separate names and since that will likely be his name if he stays like this (which I hope he does).

He even has the perfect story for a season, with Quan Yaozu being the villain, and having >!taken control of Luke Cage!< , which happened in the most recent comic, meaning that both characters for the season would already be set up.

It's not done yet, but I think this story could be a good way to add Danny to the game (Spoilers obviously)