However, with recent Chinese aggression in the SCS and ECS, we have an opportunity to open ourselves to all 10 nations and have some real influence in the area. But that means we'll have to do business with communist countries (Vietnam) and countries with less than awesome government systems. That's okay, as long as our influence is greater.
A nice idea, but practically impossible.
First, every ASEAN nation thinks that U.S. interest in the region is transitory, and only exists insofar as we decide that it's economically beneficial to us. Because of this, they are not motivated to rock the boat with China, let alone agree to take up arms against it in defense of Taiwan. Hell, we can't even get Taiwanese government to overtly stand up for itself because it wants to sustain peaceful relations with China.
Second, these nations don't have first- or even second-rate navies. The capabilities they bring to the table are extremely limited compared to Japan or South Korea, let alone the UK, France, or Germany. They are not an adequate force multiplier against the PLAN, a military alliance with them would just exist to obligate us into conflict with no real benefit.
Third, even if we could get beyond all the political hurdles, there's the technical challenge of actually integrating them into operations and without a NATO-like operational framework, everyone operates on a different sheet of music.
And to the extent that it is theoretically possible, it's certainly not going to happen within the next 10 years to counter the tripwire brute force invasion date people have in mind.
We stand a better chance of integrating Japan into NATO and getting the UK to pledge support to defend Taiwan than getting ASEAN nations up to speed in the next 10 years.
Our political leadership has challenged the military to be ready to provide flexible options to the President. Because of that, military leadership has been very hawkish about China as "the pacing threat." However, many academics and state officials remain skeptical about a PRC brute force invasion ever happening for a multitude of reasons, a top one being that the Taiwanese government is very unlikely to motivate them to do it. I tend to agree that they'll increase control over Taiwan in a more creative fashion that doesn't require fighting the USN head-on, and their navy build-up will be used as a deterrent to American intervention in a nebulous situation with tenuous public support.
My tinfoil hat theory: I think COVID-19 was part of their annexation plan.