Taking that literally the market capitalisation is the total number of coins times the current price. It's a really shitty measure as if one coin is sold for $1 million to someone with lots of dollars and a brain injury that means the market cap is in the trillions. Until the next coin sells for a few hundred dollars.

There's no limit to how high or low the price can be. In 2020 there's a good chance it'll be zero. There's another chance it'll be in the tens of thousands. You gotta decide for yourself where it might head.

This is a fun tool - http://worldbitcoinnetwork.com/BitcoinPriceModel-Alpha.html