And the slump is on. Two old-time eateries have fallen into the sinkhole we call our local economy: The 26-year-old Left Bank closed June 3, and the 18-year-old Burt & Jack's served its last supper June 29. September 11, natch, is being blamed for the exits, particularly in the case of celebrity-owned Burt & Jack's, located at Port Everglades, where would-be diners were subjected to intense security-guard scrutiny. But not only is it too late to indulge in nostalgia; it's an ongoing credo in both the restaurant biz and the poetry world: "Nothing gold can stay." So why not look ahead to the fall, when Canyon Southwest Café will open a Parisian-style lounge in downtown Fort Lauderdale on the corner of Andrews Avenue and Las Olas Boulevard? The name's not set, but the prickly pear margarita, for which Canyon is justifiably renowned, will definitely be on the menu. Frankly, that's reason enough for me not to dwell on the past.