I tend to be a big fan of the power of institutions to achieve good effects in the world, if only in making it easier for states to cooperate and share information. However, while the EU makes a great case for how this can work, I'm skeptical of the ability of any other region, particularly ASEAN+, to do the same.
This is a region with a dizzying difference in incomes (far more than the original EEC, I believe, with Singapore having 150x the per capita GDP of Burma), with very diverse political structures (from democracies in the Philippines, South Korea, and Japan, to autocratic one-party systems like China and Vietnam, to family autocracies like Singapore, and even a military junta in Burma), and with very different identities (Christian, Muslim, Buddhist, Confucian, and atheist, not to mention the extremely large number of ethnicities and nationalities). This project will have every single problem the EU had, and then some. Some of the players even want to include the US and other non-Asian countries. I expect this to be a nice idea, floated around, but then quietly set aside.