Throughout 2014, Bitcoin was repeatedly hammered into the floor, until it bottomed at $150 in 2015
This isn't a "China conspiracy", simply everyone watching the market crash and not touching it until they find a post-Gox floor. People didn't know if the floor was gonna be $400, $200, or $125. This is the least plausible conspiracy.
but currently, around 80% of the BTC mining capacity is in China. This just isn't the decentralised p2p magic internet money of freedom that Bitcoin originally set out to be.
This is where you have things wrong again, as I have explained earlier today. Your problem is located in the REAL WORLD, not Bitcoin:
That NY Times article implying China has too much power brings up an interesting point about PoW. If China is the marginal cost and manufacturing leader of the world, any open entropy system that relies on the same externalities should exactly mirror it.
So it's not an actual PoW or Bitcoin problem, but a real world problem...
The good news is, if Bitcoin is successful, nations would not be able to manipulate their currency in such a manner to cheat others with rock bottom exports. Everyone would have to play on the same level field. So the problem you claim Bitcoin has, would actually be solved by everyone adopting Bitcoin. It's probably inevitable such an event occurs and would have to be done using either Bitcoin or gold. Gold does not function whatsoever in a modern economy though, from lack of granularity, lack of portability, high friction in use, etc. So all Bitcoin has to do is not die and might be locked in to beat Gold in that inevitable event.
There is my post on trading the current state of the world economy, which applies to Bitcoin, metals, stocks, anything. Bitcoin and metals are both asymmetric trades at this point, it's all just people fretting over trying to determine if they can get a 20% deflation discount at some point:
https://bitcointalk.org/index.php?topic=1413819.msg15471618#msg15471618