A big question-mark also hangs over whether the networks can get enough big-audience blockbusters on air to allay advertiser concerns about ratings shortfalls during the strike.
Chris Boothe, a president at Publicis Groupe's Starcom USA, said: "Once the strike ends, the aftermath begins. The repercussions will be felt for a long time."
Ratings at broadcast networks have been falling since last summer, and the strike may aggravate the trend, warn observers. They also expect to see more shows such as Fox's Moment of Truth, which are cheaper than scripted dramas and do not need unionised writers.