Ok, I think that Double Barrel is right and it wouldn't even cross McNair's mind before the end of next season (and probably not even then) but....
Going hypothetical here and saying that IF McNair did pop Capers after this season (which would scare me because I think it's too soon despite all my complaining) and IF Bud in Tennessee got stupid and let Fisher go as he does from time to time when he gets mad over a losing season, the I would want the Texans to take a good look at Fisher. I don't know for certain that he'd be a good fit here in such a situation but I think they'd be insane not to consider it.
In the pro ranks there aren't too many retreads out there I'd be interested in. Mostly I'd rather see them bring up a deserving coordinator from somewhere over pulling a senior citizen out of the broadcasting booth.