How much difference could Force Z make if it survived the Japanese air attack?
Short answerIts greatest value would be as an experienced command and fleet nucleus around which ABDA could organize and receive reinforcements.
NotesThe survival of Force Z matters as much for command capacity as for the two hulls. Phillips, his staff and the capital ships could give ABDA a stronger centre than the improvised historical organization possessed. Existing forces are easier to reinforce than a fleet that must be created from nothing, potentially drawing British and American carriers into a viable multinational barrier. Japan could still mass enough force to break it, but the defence might delay operations and change the time available elsewhere in Southeast Asia.