China's growing belligerency is a near given in the short term. If it is indeed the next economic super power then being left at the mercy of the US navy and it's ability to enforce crippling embargoes is intolerable. If economic collapse, and social strife, are in the cards, then an aggressive military posture will be used as a vent t direct dissatisfaction with the PRC to a foreign adversary.
For the US the move to the Pacific is a continuation of US policy since the end of World War II. That policy is to ensure that only one nation enjoys unfettered access to the worlds oceans. Expect to see lot more confrontation with China, more assertive Japanese military, and perhaps even a reopening of a US military installation in the Philippines.