I think we have a Kris Richard dilemma.
He almost certainly needs to be the next head coach of this team. I would have liked a more experienced head coach, but it probably needs to be him. He has a connection with these defensive players and despite a few positions, they're playing decently well.
The dilemma is that I don't think you can hire a new head coach and then tell them Kris Richard is your defensive coordinator. You just can't do it (Jerry would do it, but it isn't the right move).
So either you elevate Richard or you lose a very talented coach, and maybe the latter is the better move.
Pete Carmichael Jr., Josh McDaniels, and Jim Harbaugh are all very high on my list.
When I think of the lack of experience Richard has, I remember he has a decade of coaching experience compared to the five years experience Garrett had before becoming the head coach. He's also had tremendous success whereas Garrett had not.
My biggest worry with Richard becoming head coach is if he doesn't clean house across the coaching staff.