The death at the age of 91 of Lee Kuan Yew, founding patriarch of Singapore, marks the end of a chapter, but not yet the end of an era.

The test is whether the small and vulnerable island nation can achieve the transition to a fully fledged country that can keep innovating with rapidly changing times. Lee's legacy leaves critical problems as well as opportunities.

Lee won praise for turning Singapore from a sleepy entrepot into a glossy modern metropolis and one of the richest places on Earth. The International Monetary Fund puts Singapore in third place in the world with gross domestic product per head in international dollars worth $78,762 in 2013, after Qatar ($145,894) and Luxembourg ($90,333). But his ruthlessness in dealing with critics, like communists, political opponents or tiresome journalists, and the myriad rules of Lee's "nanny state" have left many younger citizens yearning for fresher freer air.