You bring up some great points. I do agree with you mainstream adoption is probably when there's just enough average common people using a product or service.

I do think however mainstream adoption is different than mainstream awareness. For instance, back in 2010, an Apple Ipad might have just initially had a small market share when it came out but most people were aware of the product.

I do definitely believe that cryptocurrencies are definitely entering both mainstream awareness and adoption right now. My dad just asked me last month about what Bitcoin is and how we can buy some. Usually, when my somewhat not so technically inclined parents start talking to me about adopting technological stuff, it's a definite sign that something is becoming mainstream at least on some level.