the number of miners is too huge that shutting down one mining farm is not going to cause that much of a problem. and why would they suddenly be banned and shut down since they are perfectly legal as it is? it is like saying Microsoft may become illegal out of the blue so you can't use Windows anymore!
this is one of the potential concerns: the chinese government could decide to prohibit mining (unlikely but not impossible). if the prohibition were immediate and not orderly, farms across the country could be shut down, not just one. we could expect mining pools to be shut down as well.
or here's another idea: bitmain activates antbleed firmware and shuts down huge swathes of global hash rate, maybe at the behest of the chinese government.
i don't think the effects would be that drastic (aside from a price crash)---probably just significantly longer block times and major transaction backlogs. i also don't think these scenarios are likely, but you never know with china. their government is pretty erratic and has shown itself to be quite unfriendly at times towards crypto.
