"Oh, Kay!" will close Saturday night at the Kennedy Center Opera House, a $1 million loss. The revival of the Gershwin musical was to have opened Oct. 5 at New York's Lunt-Fontanne Theater.

Producer Cyma Rubin's revival of the 1927 success has been in trouble from the start. An updating of the Guy Bolton-P.G. Wodehouse book was commissioned from Muriel Resnick, author of "Any Wednesday." After the Toronto opening, Thomas Meehan, who wrote the book for "Annie," was brought in for a complete revision.

Washington first-nighters saw only a portion of this. Expensive rehearsal time was devoted to Meehan's new words. Donald Saddler, the choreographer and original director, was unofficially replaced by Burt Shevelove in the latter capacity. Shevelove's appointments with his London physician precluded his continuing as director. Star Jack Weston had trouble in memorizing Meehan's precise language. Moving the period from 1927 to 1933, just before repeal of prohibition, proved merely meaningless. A Catholic University alumna who has scored in "A Chorus Line," costar Jane Summerhays, prevailed on her friend, singer Barbara Cook, to coach her in the midst of the general flux.

Basic to "Oh, Kay's" problems was indecision at the start. Connecticut's Goodspeed Opera House, which specializes in revivals of vintage musicals, had bowed out of participation when the flossy, large-scale production was decided upon.