I don't think Bitcoin will stop at $20k so many predictions that it will land to 6 digits, the future of Bitcoin is bright and great, the present has a lot of surprises who would have thought that we will have this kind of adoption and will rule the internet.
I doubt much that Bitcoin can reach a million. It is a high volatility currency, and people will be not ready to risk with such great sums. What is BTC reaches (let us say) 500 thousand and fall to 10 thousand next day?