There was the following passage in Time magazine’s (December 1, 2016) article that came under the title, “How Castro will be Trump’s first foreign policy test”:
North Korea has both an erratic leader and nuclear weapons. Russia juggles a shrinking economy, an aggressive military and expanding role in the Middle East. China is bracing for threatened trade war, and Europe wonders if the transatlantic alliance that maintained peace for seven decades is about to be open to negotiation. So little is clear that Castro’s departure took on the quality of test case for the incoming leader of the new world.
I wonder what is the subject of “being little clear.” Is the subject of “so little clear” that “Castro’s death can be a test case for President-elect,” or unsettled situation of the world depicted in the preceding passage to “So little is clear.” I’m struggling to judge which of ①“so … that …,” or ⓶ an inversion of “formal subject ＋that ” construction does the last line come under.