If Singapore held against Japan

How would the Pacific War change if Singapore held and the Japanese invasion of Malaya failed?

Japan's southward advance becomes harder, Allied command may shift toward a British-led structure, and submarines from Singapore can attack crucial sea communications.

Holding Singapore would make movement into the Dutch East Indies and toward Australia harder, while preserving a stronger British claim to theater leadership. The base would also let Allied submarines threaten Japanese shipping across the South and East China Seas, turning geography into a logistics weapon.