Maybe this could happen, but for me i think if this cash will extinct, more bad elements will surely grab the chance to use fraud online payments during every transactions. It can be also a security from hold-ups, theft and robbery.
There is no one in this world who can tell us what is going to happen in the future. We never know this thing. Anything can happen in the coming days. As far as I think, there is no way that we can eliminate the paper money out of this world. Paper money has its own importance and value and we cannot eradicate paper money from this society. Paper money will remain at its very own place.