yeah i agree,, there should always be an alternative for now bitcoin maybe an alternative but if bitcoin become mainstream,paper money will not become obsolete, instead it can become as an alternative just like what i qouted said, when there is a power interruption, paper money can do the thing
I do believe that paper money is not going to disappear because a lot of people are used to use it for a long time already. And if paper money are going to be gone easily and going to be replaced by bitcoin, the users will going to have hard time for adopting bitcoins and going to have culture shock on it.