It is possible as you can see after the ban of China. Bitcoin was dropping hard bitcoin is stoppable. Bitcoin is not stable and it could go down with a few countries banning bitcoin.
I think it would go down, but now japan has added support to Bitcoin. So it would be a bit stable.
If something have great support and it is glaring how it could be of huge help, then we should know there are so many people out there who will be willing and set to get the lower value. You are right that bitcoin is dependent on investors and what will make bitcoin lose its value is bitcoin itself and if the proper thing is not done to make it always stand out.