Bitcoin is already mainstream. Big media platforms are writing articles about it. Also when you look the unconfirmed transactions, the amount increases every second. It passed PayPal's marketcap a couple of weeks ago. PayPal is quite mainstream, even my mother knows it.
Nah... Bitcoin has become more widely known and people are just starting to realize that there might be something to it, that's true. But it's still quite far from mainstream, albeit we're slowly getting there.
Knowing about something and using it are two very different things. A lot of people
knew about cars, computers and the internet before the general populace started
using them.
PayPal's market cap is a useless metric in this regard, unfortunately. It will be mainstream once the
userbase is the size of PayPal.
It depends on how you define mainstream. I mean you and I consider it as normal, for doing payments. But how much people need to consider it as 'normal' to be mainstream?
In my country iDEAL is widely, it's considered mainstream here. But if I would ask about it in the United States, almost nobody would know it nor use it to make payments.
And you can't really compare Bitcoin's user base to that of an one account per user service. I think it's better to compare the amount of transactions per second to that of PayPal.