I think that bitcoin will never become mainstream due to the nature of it. The only possibility I can see that it will get mainstream is via centralized parties, like easy-to-use exchanges managing the users coins.
I think you're very limited in what you know about Bitcoin; its already mainstream in some parts of the globe, and it always headlines in mainstream media. Some companies also accept cryptocurrency. Just check up Namecheap.
Here in our country, there are restaurants and services that accept cryptocurrency. You just have to check and dig deep and not just assume based on your little knowledge.
It sure is mainstream for an asset, but not for a currency. This is the different. Namecheap, and other internet companies are exceptions.