I suppose it depends on what exactly you mean by classical.
Most of John Williams’ works would probably be considered at least “in the classical style” if not completely eligible. He does pure classical too. Last year he composed a Horn Concerto for the Chicago Symphony Orchestra and a five movement piece for the Los Angeles Philharmonic for the opening of Walt Disney’s new concert hall. You may also remember that he composed the official theme music for the 2002 Salt Lake City Winter Olympic games.
I’m only a casual follower of classical, but I’m unaware of anyone who commands anything like the respect that Bach and his contemporaries do. It is also important to remember, however, that several quite-well-known composers are fairly contemporary. Benjamin Britten, a well known English composer of many operas, some symphonies, and religious music as well, only died in 1976. Aaron Copeland, American composer of several ballets (including ‘Rodeo,’ the current “Beef, it’s what’s for dinner” music) and symphonies died in 1990. Carl Orff, best known for the ‘Carmina Burana’ (you’ve heard it before…at least the opening…it’s the dramatic music used for often used for climactic, epic fight scenes) died in 1982. Dimitri Shostakovich was a very prolific Russian composer who died in 1975. Heck, Igor Stravinski only died in 1971.
If I had to pick someone who’s alive and composing right now as a bet on whose music will still be around 200 years from now, I’d have to go with John Williams. If I had to pick someone from the 20th century, well, I don’t think you could go wrong with any of the guys I mentioned above.