Since film critic Gene Siskel died in February, questions have swirled about the future of the popular TV show he hosted with fellow Chicago scribe Roger Ebert. Well, now we know - sort of. In September, the Disney-syndicated series will change its name from "Siskel & Ebert" to "Roger Ebert & the Movies," with new theme music and rotating guest critics. Yet to be determined: whether Ebert will let colleagues give the digital seal of approval. "In respect to Gene, we're not allowing other people to use the thumbs right now," says Mary Kellogg, the Disney exec overseeing the show. "Things may change this fall, but for the time being those sitting across the aisle should not have access to the thumbs." Meanwhile, competing programmers smell an opportunity. Fox cable outlet FX, Paramount Television and the fledgling Oxygen channel are all said to be developing their own movie-critic shows.