Japan held Taiwan for a mere 50 years. In those 50 years the cultural assimilation was so strong, the Taiwanese basically considered themselves Japanese, had Japanese names, and they died and fought for the Emperor just like everyone else. The freaking former president of Taiwan who was just a child during Japanese rule is still so indoctrinated he literally defends Japan and denies the existence of comfort women and says that Koreans should just stop whining and that Japan wasn't so bad to this day.
There's no doubt that Korean national identity wouldn't really exist today or it would just be an extension to the primary Japanese one.
So yeah, Japan could've probably held quite a large swath of territories they conquered, their only mistake was simply not bypassing Philippines and leaving America alone. >>594541
They thought America was going to attack anyway (wrong), so they thought a preemptive crippling strike would force the Americans to the bargaining table, which was still pretty retarded.