If you regulate the Bitcoin with proper regulations like we see in the Japan nothing will affect the BTC price or any cryptocurrency but cheapest country like US and all will not allow BTC boom.
So they will put the struggles for sure. So soon if we boycott those countries we can see BTC go bigger.
That pretty much is what will happen even if laws and regulations were put up to control bitcoin's transaction. If anything it could pose a positive effect on bitcoin's price because people could get the impression that since it's accredited by the government, we can invest on it without any worries of it being scam or something. However, that is still up for debate, and until sufficient knowledge is gained, we wouldn't be able to really know what the answer is to this question.