Mainstream adoption is coming along. It will take time. First, we need more people worldwide to own bitcoin. Secondly, a way for them to use bitcoin very easily. I expect it too be much much easier than camera and qrcode, and less worries about being hacked and confirmation times. Until that happen, bitcoin can only be an online payment system in a niche market.
Exactly, like I said previously :
At the end it is only about knowledge...
If bitcoin is not better (so ... easy and secure to use) than any other method of payment, how can we take to see it 'mainstream'?
Wait for better infrastructure, killer app and user acceptance. I will give examples:
Remember how we used credit card decades ago? We give a card to salesperson to fill in a small form, "swipe" the carbon copy form with this roller thing, phone the credit card company for a authentication code. This used to take ages and lines were busy at peak times, so end up paying cash. Merchant fee was high, not many places accept credit cards and there was no point having one.
Remember how we send email? Logon to a terminal, select email in a menu, start typing email on a blank screen including "to:" and "subject:", press some keys in sequence, it vanishes and you hope it's sent. Attaching a file was a major operation where you have to use tools to compress and then uuencode your file. Not many people had email accounts, it is much quicker and safer to fax a message to your friend.
Credit cards and email are part of our lives now. What's the difference between the ancient times and now? Technology, infrastructure, app interface, and common availability. These are what Bitcoin needs to have to go mainstream.