It wasn't until the 1960s that televising sports became so expensivethat multiple sponsors were needed to underwrite the cost--and the need for ever more commercial breaks during games.
But Spielberg has indicated boredom with action films in some recent interviews, and though no explanation was offered for the delay, aside from a statement from Spielberg's rep thatit wasn't ready and was too expensive to move forward without a polished script, the "Lincoln" filmmaker may simply not be as enamored with the brutal extinction story as he once was.