Gustavo Dudamel, who was to have conducted the New York Philharmonic this week in Vivier's "Orion" and Bruckner's Ninth Symphony, has the flu and has been replaced, in the same program, by Manfred Honeck. Next week another exciting conductor of the new generation, Pablo Heras-Casado, makes his Philharmonic debut in Britten's Four Sea Interludes from "Peter Grimes," Bartok's Third Piano Concerto (with Peter Serkin) and Shostakovich's Tenth Symphony.