As each ASEAN country has its own position on China and the Quad, Southeast Asia risks being torn between great powers.
Given the commonality and contradiction of interests that India shares with China, New Delhi’s participation in the Quad is not a move to antagonize China.
What if the United States withdrew its strategic commitment to allies in the Indo-Pacific? Taking that hypothesis seriously, Hugh White's latest essay, "Without America: Australia in the New Asia," suggests that Australia does not have any other option than engaging China—and neither does the rest of Asia.
Check out here for more research and analysis from Asian perspectives.