it is not yet mainsteaming as it could be and perhaps it will never go totally mainstream. As I cannot imagine my grandma using Bitcoins. And this is what indeed mainstream would mean - bitcoin for everyone
But indeed it is spreading widely and it is very good!
My grandad has been quizzing me about Bitcoin as he thinks they will be great for travelling if more ATM's pop up. He gets very disgruntled with currency exchanges and banks, he said the idea of having bitcoins and swapping them for local currencies with people / ATM's seems a fantastic idea.
So there is yet hope that some of the older generations will see their utility, although my grandad is a little clued up when it comes to these things as he is a big advocate of gold over cash.
well but when it comes to install a wallet or resync a blockchain or do a transaction and check it on a blockchain or some other simple issues our granddads can have a problem with figuring out how things works and they will find it hard in their age to learn from forums or tutorials... but still some of them will use it for sure.
I know we have few forum members older than 70
it depends on personality. But it is much easier for younger.