Conan O'Brien could well be headed to Fox after making it clear to NBC that he will not go graciously into the later night. But a channel-changing question that is making the rounds has more to do with what the drama unfolding between O'Brien and former Tonight Show host Jay Leno says about NBC and its agreed joint venture with Comcast. If nothing else, the lack of replacement programming for the slot Leno is vacating, and the purported profitability NBC still enjoyed by having a cheaper, single-star variety show in a traditionally pricey prime-time slot, raise an obvious question -- why the rush?