There are many miners spread all around the world and just as many merchants and bitcoin users. China might dominate
Bitcoin mining, but they are not the only miners/users/merchants. We will take a huge hit if we lost China, but we will also
not go down without them. Asic chip manufacturing will have to move to Silicon Valley, if the Chinese market stops.

Correct, even china has a big contribution in mining of bitcoin still they not hold or can stop bitcoin to progress since now lot of countries are accepting bitcoin and i think all those country has own mining sites to produce bitcoin.
And i think china can not blocked thr whole internet access in the whole world every country has own isp and not depending on china.