As the 2012-13 television season winds down, it is becoming apparent to many analysts that the broadcast networks are facing their gravest challenges ever. Writing today (Tuesday) in Advertising Age, Horizon Media analyst Brad Adgate observed that for the first time during a regular season, two cable TV series, History Channel's The Bible and AMC's The Walking Dead, ranked in the top-ten among all television shows, with Dead the highest-rated scripted show on television among the 18-49 age group. The audience-delivery gap between broadcast and cable, which has gotten smaller each year, is becoming negligible, Adgate wrote. With competition from online rivals like Netflix and YouTube an additional factor, TV penetration this season was the lowest in over 40 years, Adgate also noted. The networks are getting picked at from every direction, veteran Merrill Lynch media analyst Jessica Reif Cohen told Monday's New York Times. This year was the tipping point, she said, when the [broadcast] television ratings really fell apart.