His presidency will certainly set the stage for what the 21st century will ultimately look like.
If you look back at history, you will see that the definitive character of any given decade is established only in the third year or so into it—as though people need time to assimilate that a new decade has been ushered in: the Fifties only began after the Korean War and the death of Stalin (1953); the Sixties only got swinging with the assassination of Kennedy in Nov 1953 and the Beatles’ appearance on the Ed Sullivan Show three months later; the Seventies with the Yom Kippur War (1973) and the oil boycott that followed—etc. etc.
When it comes to centuries, it seems that they come into their own only in the middle of the second decade: the eighteenth century really began with the Treaties of Utrecht (1713) and death of Louis XIVth (1715); the nineteenth century really got underway once Napoleon was finally defeated in 1815; and the twentieth century was defined by World War I and its aftermath.
It was very hard to anticipate in the runup to this decade what would be the defining factors in this century—possibly because there are so many critical ones at play: climate change and clean energies; Peak Oil; unrest in the Arab world; the rise of China and India; Russian aspirations; etc. True to form, two of the most defining events in 2016 were unforeseen and unpredictable: Brexit, and the election of Donald Trump.
The 1910s saw world power shifting from Great Britain and other European powers to the United States. The 2010s may well see a similar shift from the USA to China. A lot depends on how Trump plays his hand.
(Originally written in reply to a question at Quora.com).