I agree with you on the Hero for Hire thing, but we’re still in origin story territory right now. That could be coming up. Being an ex-con is a big part of his backstory, but I think you can tweak that to “serious trouble with the law” without losing the character.
I’m pretty sure the only reason they didn’t actually name him Luke Cage is that Marvel isn’t sure what they want to do with the character yet, and didn’t want to commit him to this show.
I have very, very little doubt that Richards will come back. It’s a Joss Whedon show. I put it at about 80/20 that Amy Acker shows up sooner or later. I highly suspect Richards will be full cast member by the second season. I wouldn’t be at all surprised if his next appearance, he’s working something very similar to the Hero for Hire gig, or at the very least, trying to monetize his superpowers in a way that gives Shield agita. I doubt the show will go so far as to ever actually call him Luke Cage, or Power Man. I’m virtually certain that we’ll see frequent gags referencing how similar he is to Luke Cage. Particularly around December.
On the other hand, there’s always an outside chance we’ll see a scene like this:
Coulson: Mike Petersen is dead. We need to build you a new identity. What would you like your new name to be?
Mike: Uhh… I never thought about it.
Coulson: Well, who’s your favorite movie character?
Mike: Luke Skywalker?
Disney marketing would love it, at least.