I think to everyone could use bitcoin as the main currency bitcoin hast to reach very high price to be shared among all people in the world. i am talking about the number of bitcoin which is limited by the number of 21 milions which will be not enough for all population which is close to 8 miliards. So in the use will be only satoshies and only very rich people will have some bitcoins. That does not look as an utopia to me, it is our possible future. i think even Dollar and Euro will have crypto form one day.