Final answer:
Paris is the least likely city to be a significant player in international shipping, as its inland geographical location does not favor a marine shipping hub like coastal cities such as New York or Singapore.
Step-by-step explanation:
The city least likely to have become important in international shipping between New York, Singapore, Sydney, and Paris would be Paris. While cities like New York and Singapore are well-known as major international shipping hubs with extensive port facilities and prime locations on the coast, Paris does not have the geographical advantage of a coastal location. This fact, combined with the historical context that Paris was rebuilt by Baron Haussmann in the second half of the nineteenth century, focuses more on its modernization than on becoming an international shipping center, makes Paris the least likely city to be prominently involved in international shipping.