Trump's so-called "trade war" with China was never any failed attempt at relations. It was a way to get American companies out of China before the inevitable crud hit the fan. With Hong Kong's government ignoring it's people, we can see Trump's wisdom with China.
One million people in a population of just over 7 million protested a Beijing-backed extradition law in Hong Kong. Protests continued all week until a second, larger march returned one week later. What in the world is happening in the Far East? To understand Hong Kong, first take a look at Taiwan.
Much like the Asian Mad Scientist Theorem for North Korea, consider the Taiwan Schedule Theorem, as follows: Unknown to the world, China has a military expansion schedule which requires possession of Taiwan. By a certain time, Beijing wants to use Taiwan's harbors to anchor China's Navy. Anything that threatens or delays that schedule causes China to take more extreme steps elsewhere, in fact anywhere, anyway. This isn't truth; it's a theorem that explains a lot.
For example, the DPP being elected in 2016 meant a slow in China's schedule for Taiwan—according to this theorem. That led Beijing to lean on Taiwan's allies, making them break off formal relations with Taipei.
With this theorem in mind, the goal of the US would, then, be to make as many disruptions with China's "Taiwan schedule" as possible, provoking China to exhaust its "other" ways to respond to schedule delays. Trade would be one way China could respond to schedule delays. But, the US trade war already removed "trade" as way to retaliate.
Another way China expands its power is through unofficial loans. Sri Lanka had to surrender a strategic sea port to China because of debt. Moreover, if countries borrow Chinese money off the books, then government bond values are inaccurate. Under-the-table lending is another rout China can take if the "Taiwan schedule" gets delayed, but that's been exposed and won't be so easy in the future.
China's getting boxed-in and Taiwan absorption seems farther and farther away.
With snowballing US-Taiwan cooperation—including the FBI scene last week, also including the $2 Billion in arms sales—China will see more delays. Protesting the G20 set for June 28, 2019 in Osaka would be another way Beijing could retaliate for delays in absorbing Taiwan. But, Trump already promised tariffs on yet another $300 Billion in goods if Xi Jinping doesn't show.
Chinese ambassadors to G20 countries are promoting anti-US sentiment. Will those countries be likely to side with China against the US just because a Beijing ambassador told them what to do? Even Hong Kongers don't like Beijing telling their CEO what to do. Perhaps Beijing doesn't know that. Perhaps Beijing knows, but doesn't care. Perhaps everyone "kowtowing" to China's demands over the last 40 years has led the Chinese to believe they are more influential than they really are. Beijing doesn't seem to be aware of where it stands with international opinion. But, it might find out soon.
Does any Chinese president show up where he is not welcome? Think about that...
With Trump's G20 threat in place, if Xi Jinping shows up at G20 where his anti-US diplomacy efforts "un-welcomed" him, then people will think he succumbs to threats and is weak. If he doesn't show, then Trump will lecture China publicly about "keeping a schedule" while Xi's country faces tariffs on $300 Billion of goods, and Xi will be seen as weak. More importantly, with new tariffs, China would be even less able to retaliate to delays in the "Taiwan schedule". Either way, drama over G20 exhausts China and leads to a checkmate.
If Taiwan is considered a playing "card", then it is a "trump" card, as they say. Taiwan might be a chess piece, but not one that gets sacrificed. Taiwan may be the pawn-turned-queen to hold the king in check at the end game.
Now, consider Hong Kong, where a "to other countries including China" extradition law brought out 1 Million Hong Kongers in protest, twice. CEO Carrie Lam outright ignored the protestorstwice. She's sad—not about her proposed extradition law, but that the law is opposed. Ignoring 1/7th of the population when they march in the streets is a bad idea in any country, in any universe. But, Carrie doesn't care, thus reflecting the worldview of any Beijinger.
Taiwan responded by deciding that it would not cooperate with the Hong Kong extradition law, even if passed, until "human rights" were addressed and only if Hong Kong heeded the opinion of its people in choosing whether to pass the law. Without Taiwan's support, the largest—if not only—reason known to the public for the law has vanished. And, it's all because of Taiwan.
One important factor in the "Taiwan schedule" is the upcoming election. Things seemed to be leaning toward Mayor Han of Kaohsiung for the KMT-Nationalist party. But, the events in Hong Kong over the past week have weakened Han and almost certainly assured a second term for Taiwan's incumbent, President Tsai. That means only more delays in the "schedule"
If Beijing can't get a grip on Taiwan quickly, Beijing will tighten its grip on Hong Kong even more.
But, Hong Kong is small and already attached to the mainland and doesn't lend itself to much in the way of retaliation. Too many changes in Hong Kong law and countries will break treaty with Hong Kong and the "Asia's World City" show will be finished. Once Hong Kong is no longer sufficient for Beijing to lash out over delays with Taiwan, the only retaliation left will be to invade Taiwan. That was Washington's goal all along—a fight for Taiwan that requires Pentagon intervention—and long-term presence after—and China started it.
Beijing might be willing for a pro-unification candidate to win Taiwan's election. But, if other things crowd in too quickly—say the US normalizes with Taiwan—the 2020 election wouldn't help the "Taiwan schedule" either way. Beijing needs to give Washington a reason not to formalize ties with Taipei, and so far they haven't. G20 will decide a lot; China voting "absent" will decide a lot more a lot more quickly. Based on this Taiwan Schedule Theorem, expect more jeers and insults leading up to G20, from both sides, at the end of this month and expect Beijing to try every way to tighten its grip on Hong Kong.