The Asia that greets the next occupant of the Oval Office - whether a Republican or another Democrat - will be very different from the one that President Barack Obama faced in 2011, when he first announced America's strategic pivot to Asia.
The challenge for the next president, say Washington observers, is thus to find a way to maintain the trajectory of the Obama years without losing sight of potential flashpoints.
TRANS-PACIFIC PARTNERSHIP (TPP)
In October last year, 12 Pacific Rim countries capped nearly a decade of negotiations by agreeing to a mammoth free trade agreement known as the TPP. The pact now awaits ratification by the legislature in each country, but its passage in the United States is far from certain.
Failure to see it through will likely be seen as a diplomatic and economic disaster for Washington.
President Obama's rationale for the pact when lobbying Congress has been predicated on the deal allowing the US to write the rules rather than China. But most analysts say it goes well beyond that. Failure to deliver on what the administration has repeatedly insisted was its top policy priority would hurt US credibility in the region, and undermine the economic plank of rebalance. US engagement in the region would thus be focused too much on its military.
"The TPP could be the single biggest asset for the next president when trying to engage the region," said Dr Patrick Cronin of the Centre for a New American Security. "We may still be able to achieve it if it doesn't pass this year, but we will have to start from scratch."
SOUTH CHINA SEA
The territorial disputes in the South China Sea remain one of the bigger headaches for Washington.
The US has long insisted that its primary interest in the issue is simply to ensure freedom of navigation and overflight. To that end, US planes and ships have performed regular freedom-of-navigation patrols inside Chinese- claimed areas, much to the irritation of Beijing.
While most analysts generally want to see US commitment to such operations continue, they warn that any future US administration needs to watch out for three problem scenarios: China pushing back on US interpretation of surveillance and freedom of navigation; Chinese provocations aimed at the Philippines or Vietnam; and any sort of deal-making or diplomatic overtures from China that might affect how welcome the US is in the region.
An international arbitration tribunal's impending ruling on Manila's case against Beijing could prove a challenge though there are indications the new Philippine administration wants to set it aside.
Asean has been a little bit of a mixed bag for the US during the Obama administration with some notable successes but also a number of setbacks.
In recent years, the US has built up defence ties with countries where there was previously little or no cooperation, such as Malaysia, Indonesia and Vietnam. Defence ties have also grown with Singapore, which now hosts a rotation of four littoral combat ships and a deployment of P-8 Poseidon surveillance aircraft.
Improved ties with Myanmar are also considered a major success story, and the US takes some credit for pushing the country towards democratic reforms.
On the flip side, Washington's relationship with Bangkok and Manila is now effectively in a holding pattern, given the political uncertainty in Thailand and the election of brash-talking mayor Rodrigo Duterte in the Philippines. An ongoing financial scandal in Malaysia has also seen a drop in top-level exchanges between both sides.
Asean remains an important component of the Asia rebalance and so the challenge for the next US president is to remain engaged there.
South-east Asia had been largely neglected before Mr Obama made a commitment to attend summits held there every year. He also held the inaugural US-Asean summit in California in February. But analysts say all these efforts could easily fall by the wayside unless the next US administration makes a conscious effort to continue the engagement.
The US relationship with India is a bright spot in Washington's current Asia policy. Thanks in part to the strong personal rapport between Mr Obama and Prime Minister Narendra Modi, nearly every aspect of the bilateral relationship has seen a boost.
Both leaders exchanged state visits and Mr Obama became the first US president to be the chief guest at India's Republic Day parade last year.
In defence, legislation introduced in the US Senate recently seeks to elevate India to the same status as other close allies such as Israel and Nato.
The one outstanding bilateral issue is the stalled civil nuclear cooperation deal although there are signs that progress is being made.
Sino-US ties are among the few areas of Washington's Asia policy that have not improved under the rebalance.
Both powers find themselves increasingly in competition with each other on issues ranging from the South China Sea to cyber espionage.
"The next American administration will inherit this major power dynamic," George Washington University China expert David Shambaugh wrote in a recent report. "The question is whether such strategic competition can be peacefully managed."
He argued that the best way to manage relations with China is through "a broad and strong set of American relations throughout the Indo-Asian region, all around China".
Both countries also need to focus on areas where there is clearly common ground, like bilateral trade - the US imports more goods from China than any other country - and battling climate change.
JAPAN AND SOUTH KOREA
The two treaty allies remain the closest and most important allies for the US in East Asia. And as with other treaty allies, defence ties here have been boosted as well.
There are now about 54,000 US military personnel in Japan and another 28,500 in South Korea. The deployments are funded jointly by the US and the host countries, contrary to the assertions of presumptive Republican nominee Donald Trump. Tokyo pays US$1.7 billion (S$2.3 billion) a year and Seoul US$900 million to support US troops stationed on their soil. South Korea's bill amounts to 40 per cent of the total cost.
Analysts stress that the US should not start thinking about closing bases even if it wants to make the argument to get its allies to foot a bigger share.
"To back-pedal on our alliances and to send the signal that we might not be prepared to defend our allies would really destabilise the region," said Dr Cronin.
The hermit kingdom is one of the big question marks in Asia. While Iran's nuclear ambitions are now arguably contained within the framework of an international agreement, North Korea is a loose cannon. Its leader Kim Jong Un has moved to consolidate power and has of late been conducting a series of provocative missile tests.
Analysts disagree on what the US can do about the situation beyond building up defence ties with South Korea. Some agree with the "strategic patience" approach of the Obama administration while others say the US needs a more coercive policy, one that does not depend on waiting for Beijing to act.