I guess the best answer to that question is of course a BIG NO! Granted, China is a big contributor for the rise and adoption of Bitcoin and they are primarily the country involved with Bitcoin mining due to very cheap electricity cost.
Now, the Chinese government has its own agenda and I think in the long run Bitcoin can be running against those agenda so they are now thinking of slowly disengaging and disconnecting their citizens away from the cryptocurrency platform.
I know that whatever China will decide on the impact can be heavy on the market and this is shown with the recent decision banning the ICO projects and the unconfirmed total ban of Bitcoin exchanges though it is still a rumor and nobody would want to confirm.
Can cryptocurrency still go on and have a very optimistic future even without China as part of the equation?
Of course not.. There are other countries that are part as well and are contributors too. So,why would bitcoin die for that reason?
Its possible that it will die in the future but not because of one country even with the largest population but by other reasons like, market crash that could cause instability of its value in the coin market or an unexpected events that could cripple the internet. For me, its the other way around it might become more of an advantage rather than a bad one.
If china decided to be no longer part of the crypto world,
A large percent of crypto users will reduce from 15-30 percent atleast. Obviously, because of their huge population and their widescale of crypto users.
Bitcoin will definitely survive without them,its only a matter of time when other countries could step-in and become a major factor and contributor in the future of cryptocurrency.