You’d think the networks were East Germany the way people have been fleeing them for other television options. Well, one network struck back this month. CBS paid a reported $55 million to broadcast 10 films next season, including Field of Dreams and Born on the Fourth of July, before they’re shown on cable. CBS’s coup has to concern such pay-cable services as HBO and Showtime. After all, feature films have always been their raison de regarder. Cable got blindsided in the ’80s by the VCR explosion. Now comes this deal. It may well be time for the cable giants to rethink their programming strategy for the ’90s, such as increasing their original programming.