If trump pulls off a good result in NOKO, he would have undercut the bullyboy chinese and their homegrown proxy.
They will retreat, simply by toning down their responses amd not provokoing a full blown trade war, while masking their confusion and hiding behind bombastic articles in the global times.
Trump striking now is not a mere chance, not with so much of internal upheaval happening in china, their exports dwindling and oil prices spiking.
Chetak sir, Trump is not going to succeed / get any benefit from la'affaire NoKo. NoKo has a long term desire to unite Koreas, may be after 20-30 years when Kim Jong un wants to retire in united Koreas.
Whereas US has 'denuclearization' as the target. NoKo is just using US as an excuse to come out of clutches of China, historically Korea subjugated China, and they hate Han.
There's no benefit for US to unite Koreas. US is not serious about denuclearizing anyone (if they were serious, they would have denuclearized Pakis).
Coming to your second point of trade war, China never expected US to change its policy of support to China in trade and Business. They are yet to formulate a response, but if my prediction is correct, China while playing victim card, would dump their produce in Africa and south America, Australia, India, middle East etc, but behind the scenes, they will put additional efforts to steal trade secrets from US, before US starts really becomes no.2 in the world (they know that US doesn't have anything that Europe doesn't have, already playing divide and rule policy there, they have purchased Volvo and Mercedes Benz). In fact this trade war is likely to accelerate China's accension to no. 1 status.
It's not all negative for India in this trade war, if we play the game correct, the correct game for India to play is, to hurt itself by blocking China trade, buy the necessary from US and Europe, and start indigenisation, treat China as enemy both literally and in action visibly.
Coming to your third point, that America indeed wisely woken up (if that was what you meant), I am afraid, it's too little too late. US doesn't matter anymore.