The next decade promises to be another golden age of growth for the Strip. Steve Witkoff and hotel chain Marriott International announced Monday they will open the long-mothballed building on the Strip formerly known as the Fontainebleau in 2020. If all the investors manage to keep to their timelines, it will be one of six major projects totaling $10 billion that will open in 2020, reshaping the city’s skyline and economy. The projects, including three resorts, would increase Strip room availability by nearly 9,000, or about 6 percent. The 2020 openings would lead to the the largest year-on-year increase in rooms on the Strip since 1993, when the MGM Grand, Luxor and Treasure Island opened for business, boosting the number of Strip rooms by 10,000.