I think that the bitcoin can than collapse but of course we still have to see what is really gonna happen with the bitcoin if it will, hopefully nothing..on the other hand this will never happen...
I agree with your first point that if no one will use bitcoin then it will mean that the users are not available for bitcoin and all those who have bitcoins are just the investors and they can throw them to market any time to dump it. The better is that we use bitcoin in market everywhere for our needs so that the use is increased.