Give it a rest. Pulling out of the TPP hardly suggests that. Some us are happy about it.
Here is my personal understanding on the issue. If Trump follows through with his promises, US oversea influence will diminish, but the up side is that US economy will stablize as well. There are many long term consequences of this change of strategic direction.
To put it in a simpler analogy, the Chinese-US competition is like a martial battle. US started off stronger and in battle, if you are stronger, you press the advantage and hopefully eliminate the competition right there. However, launching an offensive takes a lot more effort than playing defensive, so as the time passes, US found out that it can't sustain the offensive, so it needs to back down and regroup.
This is why US has taken an antagonist stance on China in the past 20 years. Beginning at the collapse of USSR, US is in such military and economic dominance, it is seeks to contain China and prevent it from developing into a position that can challenge US dominance. However, as the time pass, it is clear that the current effort, (encircling China, propping up proxies, economic/technological sanctions, etc) isn't doing it and more importantly, these efforts took a heavy toll on US economy itself as well. For example, if TPP succeeds, it may tie many of its member economies such as Vietnam into US economy, this means Vietnam would have no choice but to oppose China at every turn. However, the downside is that large amount of low level manufacturing would flow to Vietnam and hollow out US' base manufacturing ability. BTW, this is pretty much what happened with later day USSR economy. Many of its base manufacturing went to east European/North Korea, etc, so USSR was able to maintain tight grasp on these nations, but since the outflow left USSR itself economically vulnerable, it had a very difficult time making reforms and ultimate led to its demise.
So basically, IF Trump managed to follow his promises, it will leave China a lot more room to expand its influence, but at the same time, it will also means stablization of US economic structure and the China-US competition turning into an even longer game.
Now is it a good choice or bad choice? Well, implementation difficulty aside (which I have huge doubts), from US perspective, it is, in reality, somewhat a no-win scenario. Basically, direct containing Chinese development has been a failure even when US hold the overwhelming military and economic domiance and if US continues down this path, it would be in trouble within a few decades. However, letting China develop freely would means a few more decades down the road you would probably face a China that has the military and economic dominance. Of course, that would be long past Trump's time or even our time, but that's the gist of it.
