I can guarantee you.... there will always be a country that would give a big f_ck you to the rest of the world ...and they will allow Bitcoin and Crypto mining. When the hashing power goes down... the difficulty goes down and these people in those countries will once again be able to mine Bitcoin with GPU's and CPU's.

You will even see people moving their whole Bitcoin operation from these "banned" countries to the Bitcoin friendly countries and everything will stay the same. (Like we saw with the Chinese banning Bitcoin mining in China)