I didn't say a permanent head coach - not even a coach at all. When they fire Kubs they can elevate Wade Phillips to that interim role. They need to have someone who will be around to evaluate the talent and has a meaningful say on their jobs next year. A "special assistant" to McNair, or some crap like that...don't care what you call it. Not someone interested in the permanent job, but talented in scouting players and providing an evaluation. Some names that, in my uneducated mind, could potentially do that are Tony Dungy, Lovie Smith, and Jon Gruden. I'm sure that there are others, but I'm generally ignorant on who are good talent evaluators and who are not (not to mention who would be available).
That's just it...any interim coach will not have a say so in whether or not these guys have a job next year. Philips will not be the permanent head coach, so why make him interim?
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As for who is available, there are numerous Super Bowl head coaches who are theoretically available...Smith, Dungy, Gruden, Cowher...all of whom are young enough to be viable, should they decide they want to get back in the coaching game. There are also several others who *may* be available...Rex Ryan and Mike Tomlin are names being thrown out, though I don't think either will be fired. I'd hire any of those guys in a heartbeat, should they be available. I personally don't see anyone other than Smith being interested at this point. Smith is McNair's kind of guy, but he's a Kubiak clone in personality (as is Dungy), and that may not be what they want.