For our current President Rodrigo Duterte, it seems that among his first potential challenges is definitely the ongoing territorial dispute primarily between the Philippines and China, although Spratly Islands remain to be a highly contested area with multiple countries staking claims. And while we could say that the many extrajudicial killings is probably another key issue but like the hostage-taking crisis the one that may matter more is the one with international impact.
Yes, the PCA Tribunal ruled in favor of the Philippines, but now the real work begins in terms of how this administration will respond to this award and how they will deal with China moving forward. This administration has made a number of statements along the lines of being open to resuming bilateral talks with China along with being open to some sort of resource-sharing agreement with the world's second-largest supower, but I have no idea how this will all play out. It sounds like he make take a friendlier stance with China than the previous administration did when it comes to issues of territory and sovereignty. Or maybe his secretaries and other cabinet members with more direct access to the president have actually engineered things to happen this way without Duterte knowing everything. There's far too much room for theories and speculations at this point.
Then again, it's hard to say whether a foreign relations issue will stir up nationalistic fervor and will somehow unite us against China. Or it may not matter so much to the average Filipino living a hand-to-mouth existence.
Regardless of possible outcomes, the world is watching.