Delta Air Lines customers are getting used to first class. Revenue from the pricier, roomier seats toward the front of the plane could eclipse sales from standard coach seats for at least a quarter or two next year, Delta executives said Thursday. In the last quarter, Delta said ticket revenue from its premium cabin rose 9% from last year to nearly $5.8 billion, while main-cabin ticket revenue fell 4% from a year earlier to just over $6 billion. CEO Ed Bastian said he's seen no sign of premium-