I don't usually initiate WWII questions, but have a few to post now. The first messages concerning the attack on Oahu started tricking into the US military HQ on PI around 2:00 am 8 Dec. With that as a PoD wank the US defense to the point of inflicting a strategic defeat on the Japanese invasion of PI. That is the Japanese may have a tactical or operational success in getting ashore, or having a enclave on Luzon, but fail to defeat the US/PI army.
Some of the obvious items may be:
Not find the bulk of the FEAF concentrated on Clarks Field when the Japanese air strikes arrive after 10:30 am.
Asiatic fleet, or at least the submarine fleet remains effective & inflicts some damage on the invasion fleet.
Rapid & concentrated counter attacks on the landing sites.
Practicality of reinforcement of the FEAF via the DEI south route during January.
Supply situation of the PI Army beyond December.