As the chief architect of modern Las Vegas, and a visionary who didn’t understand the meaning of subdued, Steve Wynn spent more than three decades luring visitors to the Strip with his opulent hotels, fantasy-filled casinos, fine dining experiences and luxe shopping. But now, the question on everyone’s mind is: What is the $18 billion Wynn Resorts casino and hotel empire without Steve Wynn? Hours after an unscheduled meeting of Wynn Resorts’ board of directors on Tuesday, Mr. Wynn, a 76-year-old billionaire, suddenly resigned as the chairman and chief executive of a casino conglomerate that stretches from Las Vegas to...