Bitcoin will go mainstream surely as the change has already begun.We can not just see the speed of change it is much more faster than we imagine.It is inevitable now as lot of the water has flown under the bridges.Governments as well as bankers are failed to stop Bitcoin in last couple of years.A totally new era of financial freedom and privacy is to come soon.
I don't think there's anything guaranteeing mass mainstream adoption. Sure it might and it it does go there it will take several years but part of me just thinks most of the general public just has no need or desire to use bitcoin so the mainstream will largely avoid it. I thiunk it will still have its niche uses online and in some industries but will remain relatively underground still. I hope to be wrong though.