China will likely ban all Bitcoin mining soon

“When all mining activities are banned in China, it will be a turning point for the fate of bitcoin, as a large chunk of its processing power is taken out of the picture.”

Taking out X% of mining power means the network slows down correspondingly until the next difficulty adjustment. Since the difficulty adjustment happens every 2 weeks normally, a 50% drop may mean that the next adjustment is 4 weeks away. There is a limit how much the network can adjust in each round, so a big drop can disrupt the network temporarily, but it seems unlikely that it would be "a turning point for the fate of bitcoin".

Additionally, the mining hardware will likely be exported and used elsewhere, so I'd expect a part of the hash power to re-appear over the next month or so after a ban.

Electricity is subsidized in many developing countries and the miners significantly siphon off of the primary resource that keeps them(farmers and others who come out of the poverty cycle) going, significantly increasing the odds against such people. Why did it take so long? India and many other countries would ban them outright - sooner or later.