This year Luciano Pavarotti lost 90 pounds, sold millions more CDs, and outperformed rival tenors Placido Domingo and Jose Carreras in a televised songfest seen by 500 million viewers worldwide--and he hasn't canceled any gigs yet. But his fabled voice is showing signs of wear: it sounds a trifle frayed in the upper registers and is no longer laser sharp. Which means that even though he's booked through the end of the decade at all the major houses except the Lyric (which banished him for canceling once too often), his distinguished career on the opera stage may be heading into its twilight. Of course his other, more lucrative career--singing medleys of operatic arias to hordes of less demanding fans in pop venues and on TV--will probably go on and on, sustaining its momentum on his charm and mystique. Pavarotti is, after all, at once a marvel and a caricature. For this Rosemont Horizon concertlikely to be his only local appearance for a while--Pavarotti will stay true to his Italian heritage, proffering mostly arias by Puccini, Verdi, Donizetti, and Leoncavallo. Expect encores galore. Wednesday, 8 PM, Rosemont Horizon, 6920 Mannheim, Rosemont; 559-1212 or 708-635-6600.