Kathie Lee Gifford dropped a bombshell on “Live with Regis & Kathie Lee” Tuesday morning. She said she will not return to the syndicated morning show once her contract expires. This is not the first time Gifford has threatened to do this since she and Philbin — who, as host of the primetime ratings phenom “Who Wants to Be a Millionaire,” is ABC’s golden boy — began the show together in 1989. (Philbin has just renegotiated his network contract, which was set to expire in 18 months and which covers his “Live” duties.) Kathie Lee said she will leave in July, at the start of her summer vacation, and then not return. Speculating on the show this morning as to who could replace her, Philbin suggested he might host the show alone. Last week Gifford guest-hosted “Late Show” on CBS, sitting in for David Letterman. (Her stint drew mixed reviews, as does most everything she does.) She also recently filled in for Carol Burnett in the Broadway musical review “Putting It Together.” Gifford, 46, is married to former football star Frank Gifford, 69. They have two children, Cody and Cassidy.