A Revolution in Prime Time, but Will It Work?

On Monday night, when Conan O'Brien officially takes over "The Tonight Show" from Jay Leno, it will mark an unusually peaceful transition of power in Hollywood. Then comes the revolution. NBC's decision to move Leno to his own talk show at 10 p.m. in September is not only the signature television event of this season, it may be among the most pivotal changes since the network evening newscasts were expanded to 30 minutes, from 15, in 1963. If successful, "The Jay Leno Show" at 10 p.m. could reshape prime time by leading other networks to move to less expensive shows, pushing more programming to cable and rewriting the financial underpinnings of entertainment production. If it fails — as skeptics, including many rival network executives, predict — then NBC will be left scrambling to find fill five prime-time hours a week.