I don't think that a Bitcoin mining ban in China will increase the scarcity of Bitcoin.
A crypto mining ban in China will create some short term problems,like transaction fees and confirmation time going up for a while.The mining difficulty will be adjusted and the transaction fees will return back to normal.
I don't see any negative sentiment about crypto miners going outside of China-The FUD coming from China will stop and all the noobs,who are complaining about Bitcoin being too centralized,because of the Chinese miners(which is false),will have to shut up.