suppose that 30% on electricity on btc miners will take place ... wouldn't it contribute to bitcoin scarcity due to some miners stop mining...
No. All mining just moves outside of the US. More money goes to the Chinese.
The current administration appears to be financially incompetent (or actually malicious) so it's hard to discount this could happen.
Not many people can afford to move their mining operations out side to another country and I think this only applies to companies and not people like you and me who mine. Moving it to another country means you have to trust someone to run it for you or you have to put it in a house or location you own which is a security or cost problem that most people can not over come.