if bitcoin was banned there would be a huge negative impact on the price for sure it wouldnt even matter if some of the people would still use it everyone would dump their all bitcoins to get rid of it and take out as much money as possible so lets hope this thing will not ever happen.
I think it would not give much of an effect, you know that today there are several countries that have banned bitcoin, and it does not give a bad effect on bitcoin, you can see it?