What ABDA needed to become a credible fleet

Could ABDA Command have become an effective force at the opening of the Pacific war?

Potentially, but it needed fast capital ships, a carrier, more destroyers, and a strategy that prevented the rapid loss of Singapore and the Malay barrier.

ABDA's weakness was a force-structure and timing problem rather than simply a shortage of courage. A coherent fleet built around Repulse, preferably Prince of Wales as well, an aircraft carrier, and more destroyers would have made the existing cruisers and destroyers much more useful. Japan would then need a larger force and more time to defeat it. The wider plan also required Singapore and the Malay barrier to hold long enough for that delay to matter, including stronger artillery against Japanese landings.