I think, no, unless the idea "Coin of things" come true because people still need cash to pay for real shop, they can't just buy things online everyday, over and over again
I think so, only when everything all over the world can be paid with Bitcoin or e-currencies will cash disappear because people doesn't need to use cash to pay for their lives
I think you're right, things disappear when people don't need them, so money can not disappear if people keep using money in the real life