In Las Vegas, Showing Cards To Keep Ante From Rising
Kirk Kerkorian makes unsolicited $4.5 billion bid to buy Mandalay Resort Group, deal that would give his MGM Mirage a virtual hammerlock on Las Vegas's best-known and most upscale hotels and casinos; price represents 13 percent premium over Mandalay's share price, but that may not be enough because most analysts now have 12-month target price for Mandalay of between $68 and $80 a share; Mandalay's shares rose 10 percent on June 4 after it reported near doubling of first quarter earnings, to $87.3 million and cited surge in popularity for Las Vegas; investment banks seek to interest MGM Mirage rivals in Mandalay; antitrust experts suggest that MGM Mirage could be forced to sell some hotels on Strip to placate regulators; Kerkorian photo (M)