It will not likely happen in few years away but it will definitely later happen. Bitcoin marketcap has increased a lot. It has over $2 trillion marketcap right now. If bitcoin will get to $1 million, be expecting it to have $20 trillion marketcap. That can not be easily achieved but it is possible. It can take up to a decade before something like this will happen.
You make a really good point about market cap, To achieving $20 trillion is a significant challenge, but it's definitely possible over the long term