One of its latest shows, Robert Rauschenberg in China, draws a big crowd of young visitors. [Photo provided to China Daily]

"The Ullens are after all aged, and it (UCCA) is not a family business that can be inherited. It's not their duty or obligation to stay on," says Tang Xin, director of Beijing-based Taikang Space.

Li Suqiao, a critic in the Chinese art market, says: "Thanks to Guy Ullens' persistence ... He has shown enough kindness by supporting the center with 10 percent of the profits from selling his collection."

People are wondering who will take over UCCA's management, a mature Chinese private art museum but now also a hot potato. The center doesn't profit from representing artists like art galleries do, nor can it gain from selling or loaning collections - it has no collection of its own and shares no connection with Ullens' collection.

According to Xue Mei, chief executive director of UCCA, the operation of the center cost almost 41 million yuan in 2015 and the ratio of Ullens' investment decreased from 100 percent to 25 percent.

The center has been diversifying its sources of funds over the past five years. Annual sponsorships by enterprises and 49 members of its board of trustees contributed about 35 percent in 2015 and its art store, opened in 2012, brought in 20 percent. It also holds an annual charity auction at year end and the proceeds last year were 10.9 million yuan.