SEOUL — Things looked bright for Samsung Electronics in 2016. The company had just announced South Korea’s biggest-ever corporate takeover. Halfway around the world the future U.S. president was also using a Galaxy smartphone to tweet scathing attacks against the company’s archrival Apple. Trump swapped his Galaxy for an iPhone. More significantly, he launched a trade war that radically altered the global tech landscape, and with that Samsung’s future. Today, the world’s biggest smartphone maker must grapple not only with the uncertainty of the trade war, but also a slump in its mainstay chip business, the rapid rise of Chinese tech rivals and a resurgent Apple. Worse still, the man who is expected to continue steering Samsung through these challenges may be on his way to jail. 2016 already seems like a distant memory to many at Samsung, a company that in many ways defines South Korea. Back then Lee Jae-yong, vice chairman of Samsung Electronics but in reality the group’s de facto leader and heir apparent, had just spearheaded the $8 billion acquisition of Harman, the U.S. audio components maker. The news conference announcing the deal was wa...